Types of Immune System Cells - MCAT Biological and Biochemical Foundations of Living Systems
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Which of the following innate immune cells primarily protects against bacterial infections?
Which of the following innate immune cells primarily protects against bacterial infections?
Neutrophils contain antimicrobial products in vesicles, which are secreted when they come into contact with foreign cells. Neutrophils primarily mediate reaction to bacterial infections and are the primary component of the white pus found in bacterial inflammation. Eosinophils respond to parasitic infections and basophils to allergies (IgE). Megakaryocytes produce platelets.
Neutrophils contain antimicrobial products in vesicles, which are secreted when they come into contact with foreign cells. Neutrophils primarily mediate reaction to bacterial infections and are the primary component of the white pus found in bacterial inflammation. Eosinophils respond to parasitic infections and basophils to allergies (IgE). Megakaryocytes produce platelets.
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Which of the following immune cells primarily mediates reactions to parasitic infections?
Which of the following immune cells primarily mediates reactions to parasitic infections?
Eosinophils primarily mediate reactions to parasitic infections, including worms. Neutrophils respond to bacterial infections, and basophils to allergies (IgE). Megakaryocytes are responsible for making platelets.
Eosinophils primarily mediate reactions to parasitic infections, including worms. Neutrophils respond to bacterial infections, and basophils to allergies (IgE). Megakaryocytes are responsible for making platelets.
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Which of the following immune cells is involved in responding to allergies and drug reactions?
Which of the following immune cells is involved in responding to allergies and drug reactions?
Basophils and mast cells are responsible for secreting factors like histamine in response to allergens and drugs. Release of the histamine can cause throat constriction, hives, and inflammation. Eosinophils mediate reactions to parasitic infections and neutrophils to bacterial infections. Megakaryocytes produce platelets.
Basophils and mast cells are responsible for secreting factors like histamine in response to allergens and drugs. Release of the histamine can cause throat constriction, hives, and inflammation. Eosinophils mediate reactions to parasitic infections and neutrophils to bacterial infections. Megakaryocytes produce platelets.
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Which of the following is NOT an antigen presenting cell?
Which of the following is NOT an antigen presenting cell?
This question asks which of the following is NOT an antigen presenting cell, therefore, any option that is an antigen presenting cell in the immune system is an INCORRECT answer.
During an immune response, the cells involved in antigen presentation are dendritic cells, macrophages, and B-cells. T-cells, then, must be the answer choice that is NOT an antigen presenting cell, and thus is the correct answer.
This question asks which of the following is NOT an antigen presenting cell, therefore, any option that is an antigen presenting cell in the immune system is an INCORRECT answer.
During an immune response, the cells involved in antigen presentation are dendritic cells, macrophages, and B-cells. T-cells, then, must be the answer choice that is NOT an antigen presenting cell, and thus is the correct answer.
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Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Which of the following does not play a key role in the adaptive immune response?
Duchenne Muscular Dystrophy is an X-linked recessive genetic disorder, resulting in the loss of the dystrophin protein. In healthy muscle, dystrophin localizes to the sarcolemma and helps anchor the muscle fiber to the basal lamina. The loss of this protein results in progressive muscle weakness, and eventually death.
In the muscle fibers, the effects of the disease can be exacerbated by auto-immune interference. Weakness of the sarcolemma leads to damage and tears in the membrane. The body’s immune system recognizes the damage and attempts to repair it. However, since the damage exists as a chronic condition, leukocytes begin to present the damaged protein fragments as antigens, stimulating a targeted attack on the damaged parts of the muscle fiber. The attack causes inflammation, fibrosis, and necrosis, further weakening the muscle.
Studies have shown that despite the severe pathology of the muscle fibers, the innervation of the muscle is unaffected.
Which of the following does not play a key role in the adaptive immune response?
The adaptive immune response involves the presentation of antigens, identification of antigens, activation of immune response, and elimination of pathogens. Dendritic cells present the antigen to the helper T-cells, which identify it and activate B-cells and cytotoxic T-cells to eliminate the pathogen.
Natural killer cells play a key role in the innate immune response by eliminating pathogens without the recognition of antigens.
The adaptive immune response involves the presentation of antigens, identification of antigens, activation of immune response, and elimination of pathogens. Dendritic cells present the antigen to the helper T-cells, which identify it and activate B-cells and cytotoxic T-cells to eliminate the pathogen.
Natural killer cells play a key role in the innate immune response by eliminating pathogens without the recognition of antigens.
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Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A key immune response to Neisseria in humans is the activity of macrophages. What is true of how macrophages combat infection?
Sexually transmitted diseases are a common problem among young people in the United States. One of the more common diseases is caused by the bacterium Neisseria gonorrhoeae, which leads to inflammation and purulent discharge in the male and female reproductive tracts.
The bacterium has a number of systems to evade host defenses. Upon infection, it uses pili to adhere to host epithelium. The bacterium also uses an enzyme, gonococcal sialyltransferase, to transfer a sialyic acid residue to a gonococcal surface lipooligosaccharide (LOS). A depiction of this can be seen in Figure 1. The sialyic acid residue mimics the protective capsule found on other bacterial species.
Once infection is established, Neisseria preferentially infects columnar epithelial cells in the female reproductive tract, and leads to a loss of cilia on these cells. Damage to the reproductive tract can result in pelvic inflammatory disease, which can complicate pregnancies later in the life of the woman.
A key immune response to Neisseria in humans is the activity of macrophages. What is true of how macrophages combat infection?
Macrophages are professional phagocytic cells. They ingest pathogens, and often use reactive oxygen species to kill pathogens via a burst of radical activity in specialized cellular compartments.
Macrophages are professional phagocytic cells. They ingest pathogens, and often use reactive oxygen species to kill pathogens via a burst of radical activity in specialized cellular compartments.
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Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
When the body recognizes that cells have become cancerous, it responds in part by mobilizing cell-mediated killing of cancer cells. What cells are most likely responsible for this killing?
Scientists use a process called Flourescent In-Situ Hybridization, or FISH, to study genetic disorders in humans. FISH is a technique that uses spectrographic analysis to determine the presence or absence, as well as the relative abundance, of genetic material in human cells.
To use FISH, scientists apply fluorescently-labeled bits of DNA of a known color, called probes, to samples of test DNA. These probes anneal to the sample DNA, and scientists can read the colors that result using laboratory equipment. One common use of FISH is to determine the presence of extra DNA in conditions of aneuploidy, a state in which a human cell has an abnormal number of chromosomes. Chromosomes are collections of DNA, the totality of which makes up a cell’s genome. Another typical use is in the study of cancer cells, where scientists use FISH labels to ascertain if genes have moved inappropriately in a cell’s genome.
Using red fluorescent tags, scientists label probe DNA for a gene known to be expressed more heavily in cancer cells than normal cells. They then label a probe for an immediately adjacent DNA sequence with a green fluorescent tag. Both probes are then added to three dishes, shown below. In dish 1 human bladder cells are incubated with the probes, in dish 2 human epithelial cells are incubated, and in dish 3 known non-cancerous cells are used. The relative luminescence observed in regions of interest in all dishes is shown below.
When the body recognizes that cells have become cancerous, it responds in part by mobilizing cell-mediated killing of cancer cells. What cells are most likely responsible for this killing?
CD8+ T-cells are also called cytotoxic T-cells. They are the main agents of cell-mediated immune cytotoxicity. This function is critical for the elimination of virally infected or cancerous cells. Macrophages, in contrast, are responsible for eliminating foreign pathogens and do not attack non-foreign cells.
CD8+ T-cells are also called cytotoxic T-cells. They are the main agents of cell-mediated immune cytotoxicity. This function is critical for the elimination of virally infected or cancerous cells. Macrophages, in contrast, are responsible for eliminating foreign pathogens and do not attack non-foreign cells.
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Where do the T-cells of the immune system mature into functional T-cells?
Where do the T-cells of the immune system mature into functional T-cells?
T-cells are originally formed from stem cells in the bone marrow, however, T-cells, unlike B-cells, mature in the thymus. The thymus is a lymphoid organ located in the upper chest.
In contrast, B-cells are formed and mature in the bone marrow.
T-cells are originally formed from stem cells in the bone marrow, however, T-cells, unlike B-cells, mature in the thymus. The thymus is a lymphoid organ located in the upper chest.
In contrast, B-cells are formed and mature in the bone marrow.
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Most scientists subscribe to the theory of endosymbiosis to explain the presence of mitochondria in eukaryotic cells. According to the theory of endosymbiosis, early pre-eukaryotic cells phagocytosed free living prokaryotes, but failed to digest them. As a result, these prokaryotes remained in residence in the pre-eukaryotes, and continued to generate energy. The host cells were able to use this energy to gain a selective advantage over their competitors, and eventually the energy-producing prokaryotes became mitochondria.
In many ways, mitochondria are different from other cellular organelles, and these differences puzzled scientists for many years. The theory of endosymbiosis concisely explains a number of these observations about mitochondria. Perhaps most of all, the theory explains why aerobic metabolism is entirely limited to this one organelle, while other kinds of metabolism are more distributed in the cellular cytosol.
Some version of phagocytosis was likely the initial event that introduced a free-living prokaryote into the host described in the passage. Which of the following cells is most commonly associated with phagocytosis?
Most scientists subscribe to the theory of endosymbiosis to explain the presence of mitochondria in eukaryotic cells. According to the theory of endosymbiosis, early pre-eukaryotic cells phagocytosed free living prokaryotes, but failed to digest them. As a result, these prokaryotes remained in residence in the pre-eukaryotes, and continued to generate energy. The host cells were able to use this energy to gain a selective advantage over their competitors, and eventually the energy-producing prokaryotes became mitochondria.
In many ways, mitochondria are different from other cellular organelles, and these differences puzzled scientists for many years. The theory of endosymbiosis concisely explains a number of these observations about mitochondria. Perhaps most of all, the theory explains why aerobic metabolism is entirely limited to this one organelle, while other kinds of metabolism are more distributed in the cellular cytosol.
Some version of phagocytosis was likely the initial event that introduced a free-living prokaryote into the host described in the passage. Which of the following cells is most commonly associated with phagocytosis?
Neutrophils are professional phagocytes of the immune system. They prevent infection by phagocytosing potential invaders.
Note, however, that neutrophils could not have been the initial cell type to phagocytose a free-living prokaryote. Neutrophils are eukaryotic, and evolved long after endosymbiosis first occurred. They are, however, still closely linked to phagocytosis in humans.
Neutrophils are professional phagocytes of the immune system. They prevent infection by phagocytosing potential invaders.
Note, however, that neutrophils could not have been the initial cell type to phagocytose a free-living prokaryote. Neutrophils are eukaryotic, and evolved long after endosymbiosis first occurred. They are, however, still closely linked to phagocytosis in humans.
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Which of the following are NOT involved in cell-mediated immunity?
Which of the following are NOT involved in cell-mediated immunity?
Cell-mediated immunity involves the response of specific cells toward an invading pathogen or organism. This is in contrast to humoral, or antibody-mediated immunity. Both of these are types of adaptive immunity, however, cell-mediated immunity involves the initial identificaiton of an unknown pathogen, while humoral immunity requires prior exposure to the antigen.
B-cells secrete antibodies and are the main actor in humoral immunity; they do not participate directly in cell-mediated immunity. Cytotoxic T-cells are activated by helper T-cells to recognize and destroy infected cells in the body. The process also involves cytokines which recruit neutrophils to digest the infected cell or microbes.
Cell-mediated immunity involves the response of specific cells toward an invading pathogen or organism. This is in contrast to humoral, or antibody-mediated immunity. Both of these are types of adaptive immunity, however, cell-mediated immunity involves the initial identificaiton of an unknown pathogen, while humoral immunity requires prior exposure to the antigen.
B-cells secrete antibodies and are the main actor in humoral immunity; they do not participate directly in cell-mediated immunity. Cytotoxic T-cells are activated by helper T-cells to recognize and destroy infected cells in the body. The process also involves cytokines which recruit neutrophils to digest the infected cell or microbes.
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One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Neutrophils are best described as being
.
One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Neutrophils are best described as being .
Neutrophils are one of the main players in innate immunity. Their response does not require having previously been exposed to the pathogen, and they are fairly nonspecific in their ability to digest foreign invaders.
As stated in the passage, neutrophils are derived from monocyctes, not B-cells or natural killer cells.
Neutrophils are one of the main players in innate immunity. Their response does not require having previously been exposed to the pathogen, and they are fairly nonspecific in their ability to digest foreign invaders.
As stated in the passage, neutrophils are derived from monocyctes, not B-cells or natural killer cells.
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One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Macrophages, similar to neutrophils, are another professional phagocyte, and a type of antigen-presenting cell. Antigen-presenting cells digest invaders, and then present their foreign proteins to B-cells and T-cells for further immune response. Which of the following is true of antigen-presenting cells?
I. They present their antigens on major histocompatibility complex molecules.
II. They migrate to lymph nodes to present their antigens to B-cells and T-cells.
III. Antigen-presenting cells form a link between the innate and adaptive immune systems.
One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.
In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.
Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.
The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.
Macrophages, similar to neutrophils, are another professional phagocyte, and a type of antigen-presenting cell. Antigen-presenting cells digest invaders, and then present their foreign proteins to B-cells and T-cells for further immune response. Which of the following is true of antigen-presenting cells?
I. They present their antigens on major histocompatibility complex molecules.
II. They migrate to lymph nodes to present their antigens to B-cells and T-cells.
III. Antigen-presenting cells form a link between the innate and adaptive immune systems.
Antigen-presenting cells do all of these functions, thus working to stimulate an adaptive response in regional lymph nodes.
Histocompatibility complex molecules, or MHCs, are keys for carrying antigens and developing antibodies. Once antigen-presenting cells encounter an antigen, they will bind it and carry it to the lymph nodes to activate the adaptive immune response, or to establish cellular memory of a new foreign antigen.
Antigen-presenting cells do all of these functions, thus working to stimulate an adaptive response in regional lymph nodes.
Histocompatibility complex molecules, or MHCs, are keys for carrying antigens and developing antibodies. Once antigen-presenting cells encounter an antigen, they will bind it and carry it to the lymph nodes to activate the adaptive immune response, or to establish cellular memory of a new foreign antigen.
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Which of the following is a granulocyte?
Which of the following is a granulocyte?
The granulocytes that participate in innate immunity have vesicles filled with chemicals and proteins, such as perforin and trypsin, that are released to kill foreign bacteria, fungi, and parasites. The granulocytes include neutrophils, eosinophils, basophils, and mast cells.
Neutrophils are involved in bacterial infections and eosinophils in parasitic infections. Basophils and mast cells are involved in allergic reactions and inflammation.
The granulocytes that participate in innate immunity have vesicles filled with chemicals and proteins, such as perforin and trypsin, that are released to kill foreign bacteria, fungi, and parasites. The granulocytes include neutrophils, eosinophils, basophils, and mast cells.
Neutrophils are involved in bacterial infections and eosinophils in parasitic infections. Basophils and mast cells are involved in allergic reactions and inflammation.
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When heart surgeries were initially performed on children, surgeons would sometimes discard the thymus because they did not know its function. These children would often die due to which lost function of the thymus?
When heart surgeries were initially performed on children, surgeons would sometimes discard the thymus because they did not know its function. These children would often die due to which lost function of the thymus?
The correct answer is that T-cells would not be able to mature. Both T-cells and B-cells are generated in the bone marrow, however, their sites of maturation are different. B-cells mature in the bone marrow, whereas T-cells mature in the thymus.
T3 and T4 are thyroid hormones, and are unlinked to the thymus. Hypothyroidism occurs due to a deficiency in these hormones.
The correct answer is that T-cells would not be able to mature. Both T-cells and B-cells are generated in the bone marrow, however, their sites of maturation are different. B-cells mature in the bone marrow, whereas T-cells mature in the thymus.
T3 and T4 are thyroid hormones, and are unlinked to the thymus. Hypothyroidism occurs due to a deficiency in these hormones.
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Where in the human body do T-Cells mature?
Where in the human body do T-Cells mature?
T-cells and B-cells are derived from stem cells that originate in the bone marrow. B-cells continue to mature in the bone marrow; however, T-cells mature in the thymus. Once they are mature, they travel through the blood and reside in the lymph.
T-cells and B-cells are derived from stem cells that originate in the bone marrow. B-cells continue to mature in the bone marrow; however, T-cells mature in the thymus. Once they are mature, they travel through the blood and reside in the lymph.
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Cell-mediated immunity involves the action of which of the following cells?
Cell-mediated immunity involves the action of which of the following cells?
Cell-mediated immunity involves all of the differentiated forms of T-lymphocytes. Cytotoxic T-cells (also called killer T-cells) are antigen-specific, and responsible for the destruction of infected cells bearing the given antigen.
Plasma cells and B-cells are part of humoral (antibody) immunity, while neutrophils play an important role in the innate immune response.
Cell-mediated immunity involves all of the differentiated forms of T-lymphocytes. Cytotoxic T-cells (also called killer T-cells) are antigen-specific, and responsible for the destruction of infected cells bearing the given antigen.
Plasma cells and B-cells are part of humoral (antibody) immunity, while neutrophils play an important role in the innate immune response.
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Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.
As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.
Di George syndrome is a genetic disorder that results in failure of thymus formation during development, and thus in immune deficiency. A doctor examines the blood of a patient with Di George syndrome. What is she most likely to find?
Type 1 diabetes is a well-understood autoimmune disease. Autoimmune diseases result from an immune system-mediated attack on one’s own body tissues. In normal development, an organ called the thymus introduces immune cells to the body’s normal proteins. This process is called negative selection, as those immune cells that recognize normal proteins are deleted. If cells evade this process, those that recognize normal proteins enter into circulation, where they can attack body tissues. The thymus is also important for activating T-cells that recognize foreign proteins.
As the figure below shows, immune cells typically originate in the bone marrow. Some immune cells, called T-cells, then go to the thymus for negative selection. Those that survive negative selection, enter into general circulation to fight infection. Other cells, called B-cells, directly enter general circulation from the bone marrow. It is a breakdown in this carefully orchestrated process that leads to autoimmune disease, such as type 1 diabetes.
Di George syndrome is a genetic disorder that results in failure of thymus formation during development, and thus in immune deficiency. A doctor examines the blood of a patient with Di George syndrome. What is she most likely to find?
The patient has Di George syndrome, which is characterized by a lack of thymus tissue. Based on the information in the passage, loss of the thymus is most likely to manifest as a deficiency of T-cells, while the presence of B-cells will be relatively unaffected.
The patient has Di George syndrome, which is characterized by a lack of thymus tissue. Based on the information in the passage, loss of the thymus is most likely to manifest as a deficiency of T-cells, while the presence of B-cells will be relatively unaffected.
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Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
One of the functions of antibodies is to facilitate the phagocytosis of pathogens by macrophages or other professional phagocytes. Which of the following organelles is likely to be found in abundance in professional phagocytes, relative to most other cell types?
Hypersensitivity reactions occur when body tissues are affected by an abnormal immune reaction. The result is damage to normal tissues and clinical illness. A peanut allergy is an example of a hypersensitivity reaction, but there are three additional broad classes.
One class involves the abnormal production or deposition of antibodies. Antibodies are B-cell derived molecules that normally adhere to pathogens, rendering them unable to continue an infection. When antibodies are produced against normal tissues, however, disease can result. Figure 1 depicts a schematic structure of an antibody.
Antibodies can be divided into two peptide chains: heavy and light. Heavy chains form the backbone of the antibody, and are attached to light chains via covalent bonding. Each heavy and light chain is then further divided into constant and variable regions. Variable regions exhibit molecular variety, generating a unique chemical identity for each antibody. These unique patterns help guarantee that the body can produce antibodies to recognize many possible molecular patterns on invading pathogens.
One of the functions of antibodies is to facilitate the phagocytosis of pathogens by macrophages or other professional phagocytes. Which of the following organelles is likely to be found in abundance in professional phagocytes, relative to most other cell types?
Endosomes function to shuttle phagocytosed material to the lysosome, where cellular digestion can take place. This means that professional phagocytes, such as macrophages, can be expected to have a larger number of endosomes than other cells that are less specialized for this process.
Endosomes function to shuttle phagocytosed material to the lysosome, where cellular digestion can take place. This means that professional phagocytes, such as macrophages, can be expected to have a larger number of endosomes than other cells that are less specialized for this process.
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The thymus is responsible for producing which of the following immune cells?
The thymus is responsible for producing which of the following immune cells?
The thymus is responsible for the maturation of T-cells. The thymus, a gland centered in the chest, allows T-cells to be tested against a "self-antigen." If the T-cell does not react against the self-antigen, it is allowed to leave the thymus and enter into circulation to detect foreign antigens. If the T-cell does react to the self-antigen, it is generally destroyed. Failure to destroy these T-cells can result in autoimmune attacks. Upon detection of foreign antigens, mature T-cells differentiate into a variety of other T-cell types and stimulate B-cells to produce antibodies.
The thymus is responsible for the maturation of T-cells. The thymus, a gland centered in the chest, allows T-cells to be tested against a "self-antigen." If the T-cell does not react against the self-antigen, it is allowed to leave the thymus and enter into circulation to detect foreign antigens. If the T-cell does react to the self-antigen, it is generally destroyed. Failure to destroy these T-cells can result in autoimmune attacks. Upon detection of foreign antigens, mature T-cells differentiate into a variety of other T-cell types and stimulate B-cells to produce antibodies.
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Which of the following immune cells is responsible for engulfing foreign bacteria, viruses, and parasites and presenting antigens to lymphocytes to initiate an immune reaction?
Which of the following immune cells is responsible for engulfing foreign bacteria, viruses, and parasites and presenting antigens to lymphocytes to initiate an immune reaction?
Macrophages are responsible for ingesting and degrading bacteria and viruses, and presenting their antigens on major histocompatibility complexes (MHCs) to B- and T-cells. Macrophages are thus responsible for mediating the initiation of an immune reaction.
Megakaryocytes produce platelets, and B- and T-cells are the lymphocytes to which macrophages present ingested antigens.
Macrophages are responsible for ingesting and degrading bacteria and viruses, and presenting their antigens on major histocompatibility complexes (MHCs) to B- and T-cells. Macrophages are thus responsible for mediating the initiation of an immune reaction.
Megakaryocytes produce platelets, and B- and T-cells are the lymphocytes to which macrophages present ingested antigens.
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