MCAT Biology : Immune and Lymphatic Systems
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Example Questions
Example Question #111 : Immune And Lymphatic Systems
Toll like receptors (TLR's) are pattern recognition receptors that recognize specific pathogen-associated molecular patterns (PAMP's) on different pathogens and induce an immune response against the foreign pathogen. Numerous immune cell types express TLR's, including antigen-presenting cells and natural killer cells. TLR's play a critical role in the recognition and induction of the immune response against viruses.
A person that has a decreased inherent ability to detect RNA viruses such as influenza and hepatitis would presumably have a defect in which specific TLR?
TLR9
TLR5
TLR7
TLR2
TLR4
TLR7
TLR7 recognizes single-stranded RNA. TLR9 recognizes DNA, TLR4 recognizes lipopolysaccharide, TLR2 recognizes different bacterial components, TLR5 recognizes flagellin.
Example Question #7 : Immune Proteins And Signals
The complement system consists of plasma proteins that can directly or indirectly be activated by foreign pathogens. This leads to the induction of a signaling cascade of reactions that occurs on the surface of the pathogens, which leads to different effector functions including opsonization and neutralization. Deficiencies in different components of complement has been linked to an increased susceptibility to autoimmune diseases, including systemic lupus erythematosus (SLE).
Which of the following would be the most likely scenario regarding how a complement deficiency would result in an increased risk of developing autoimmunity?
Complement deficiency leads to increased killing of regulatory T cells, which allow autoreactive lymphocytes to escape apoptosis.
Complement deficiency leads to a decrease in the formation of antibody-antigen-complement immune complexes, resulting in decreased deposition on tissues.
Complement deficiency leads to increased apoptosis, which leads to a decrease in the presence of self-antigens, thus altering peripheral tolerance.
Complement deficiency leads to decreased binding to self-antigens from apoptotic cells, resulting in an increased amount of self-antigen present, thus increasing the chances of encountering autoreactive lymphocytes.
Complement deficiency leads to an increase in inflammatory monocytes, which leads to a chronic inflammatory state.
Complement deficiency leads to decreased binding to self-antigens from apoptotic cells, resulting in an increased amount of self-antigen present, thus increasing the chances of encountering autoreactive lymphocytes.
The complement system is able to protect against immune responses to autoantigens through the elimination of lymphocytes that are reactive against self antigens. Complement proteins are able to coat self antigens from apoptotic cells and deliver them to developing B cells (through binding to the B cell's complement receptors) and enhancing negative selection. A defective complement system increases the amount of self-antigen present, which can lead to increased chances of binding to autoreactive lymphocytes.
Example Question #1 : Other Immunity Principles
The common precursor for all blood and immune cells, including red blood cells and lymphocytes, is found in what part of the body?
Bone marrow
Kidney
Spleen
Liver
Bone marrow
All blood cells, including erythrocytes and lymphocytes, come from the same stem cell precursor in the bone marrow. These hematopoietic stem cells give rise to both the myeloid and lymphoid progenitor cells, which are responsible for all blood cells and immune cells. This common precursor spawns cells that then differentiate into the various components of humoral, cell-mediated, and innate immunity.
Example Question #3 : Animal Biology
Which types of leukocytes are granular?
Basophils, lymphocytes, monocytes
Monocytes, neutrophils, eosinophils
Lymphocytes, basophils, eosinophils
Neutrophils, basophils, lymphocytes
Basophils, eosinophils, neutrophils
Basophils, eosinophils, neutrophils
The five types of leukocytes are: neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Three of these (neutrophils, eosinophils, and basophils) contain granules, tiny sacs containing enzymes which can lyse microorganisms. The other two leukocytes (lymphocytes and monocytes) do not contain these granules.
Example Question #2 : Other Immunity Principles
Which of the following is not a true statement regarding germinal centers?
They are transient microenvironments that ultimately produce long-lived plasma cells and memory B cells against a specific antigen.
T cells are not critical for the formation and maintenance of the germinal center reaction.
B cells that have undergone a germinal center reaction should produce antibody against a specific antigen that is higher affinity than naive B cells.
Germinal centers are sites where peripheral tolerance occurs.
Germinal centers normally form in secondary lymph nodes but can form ectopic ones in other organs including the kidneys and liver.
T cells are not critical for the formation and maintenance of the germinal center reaction.
T cells, especially CD4+ follicular helper T cells, are absolutely critical and necessary for the induction and maintenance of germinal centers.
Example Question #1 : Other Immunity Principles
Which of the following class of immunoglobulins is normally responsible for the promotion of the allergy response?
IgA
IgG
IgD
IgM
IgE
IgE
IgE plays a critical role in induction and promotion of type I hypersensitivity (allergy, asthma, etc.) normally through engagement of Fc receptors on the surface of basophils and mast cells, which primes them to produce large quantities of granules and chemical mediators (including histamines and cytokines).
Example Question #1 : Other Immunity Principles
Which is not a function of B cells?
Ability to form memory cells
Secretion of extracellular traps
Antibody production
Presentation of antigen to T cells
Cytokine and chemokine production
Secretion of extracellular traps
B cells play numerous integral roles in the immune response against foreign pathogens (viruses, bacteria, and fungi), including forming transient microenvironments called germinal centers, where they produce long-lived plasma cells that are high affinity for specific antigen and memory B cells. They also serve as antigen-presenting cells and producers of cytokines and chemokines; However, B cells are not able to produce extracellular traps, which primarily are composed of DNA and work to trap pathogens. Neutrophils produce extracellular traps.
Example Question #2 : Other Immunity Principles
Which cytokine is typically associated with the T helper 1 (Th1) response?
IL-9
TGF-beta
IL-4
IFN-gamma
IL-17
IFN-gamma
The following helper T cells are paired with the following cytokines:
Th1 - IFN-gamma
Th2 - IL-4
Th9 - IL-9
Th17 - IL-17
Tfh - IL-21
Example Question #3 : Other Immunity Principles
What is the group of diseases called when a person's immune system loses its ability to recognize its own MHC proteins?
X-linked autosomal recessive diseases
Allergies
Hypersensitivity
X-linked lymphoproliferative disease
Autoimmune
Autoimmune
Autoimmunity arises when one's immune system is unable to recognize its own MHC proteins, which could potentially lead to aberrant activation of the immune response. Furthermore, autoreactive immune cells that are normally induced to undergo apoptosis may be able to escape these tolerance mechanisms and induce tissue damage.
Example Question #4 : Other Immunity Principles
Which of the following cell types is considered to be part of the innate immune response?
T cells
Memory cells
Myocytes
B cells
NK cells
NK cells
Natural killer (NK) cells are prominent members of the initial innate immune response against foreign pathogens. They play numerous integral roles in the innate response including cytotoxic killing, cytokine production, and antibody-mediated cell cytotoxicity.
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