MCAT Biology : Adaptive and Innate Immunity
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Example Question #52 : Immune System
Inflammation is an important response of the immune system. The vasodilation of blood vessels allows for important cells of the innate immune system to move out of the blood and into the surrounding tissue. Which of the following members of the innate immune system is responsible for causing inflammation at the site of infection?
Macrophages
Dendritic cells
Natural Killer Cells
Mast cells
Mast cells
The correct answer is mast cells. Mast cells as well as granulocytes participate in the innate immune system's inflammatory response. Mast cells release histamine as well as other chemicals that allow for other cells to move from the blood stream into the tissue at the site of infection.
Example Question #53 : Immune System
The HIV virus infects which of the following cells in order to diminish coordinated immune responses against pathogens?
Basophils
Macrophages
Cytotoxic T -cells
Neutrophils
Helper T-cells
Helper T-cells
The HIV virus readily attacks Helper T-cells because these cells have a signaling-cascade effect on most immune cells. Most importantly, helper T-cells stimulate B-cells to produce antibodies. As the virus destroys the helper T-cells, it effectively negates the adaptive immune system, making the body exceptionally vulnerable to infection.
Example Question #51 : Immune System
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by the loss of tolerance to self antigens leading to the presence of high autoantibody titers. Dysregulated peripheral tolerance and hyperactive germinal centers have been proposed to be one of the driving forces behind the accumulation of high autoantibodies.
What immune cell type is the product of germinal centers and most likely the cell mediating the production of autoantibodies?
Plasma cells
Tingible body macrophages
Follicular dendritic cells
Natural killer cells
Follicular helper T cells
Plasma cells
Plasma cells are the main product of germinal centers and are potent antibody factories. Dysregulated peripheral tolerance and germinal centers can lead to the production of plasma cells that are reactive towards self-nuclear antigens.
Example Question #55 : Immune System
Which of the following is an example of a primary lymphoid organ?
Lymph nodes
Spleen
Peyer's patches
Thymus
Tonsils
Thymus
The thymus is a primary lymphoid organ (along with bone marrow). The thymus is where T cells differentiate and mature. All of the other organs listed are secondary lymphoid organs, where lymphocytes reside and respond to antigenic challenges and foreign pathogens.
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