MCAT Biology : Immune System
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Example Question #121 : Immune And Lymphatic Systems
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. There are several underlying causes behind SLE, one of which is a dysregulation in the clearance of apoptotic cells, which can lead to secondary necrosis. This leads to the leakage of danger signals which contributes to the loss of peripheral tolerance and chronic inflammation.
A deficiency in the clearance of apoptotic cells can be attributed to which immune cell type?
Macrophages
Natural killer cells
Cytotoxic T cells
Plasma cells
Germinal center B cells
Macrophages
The defect in clearance of apoptotic cells in SLE is mainly attributed to macrophages, which serve integral roles in phagocytosis of dead cells and debris. An inability to clear these apoptotic cells over time leads to secondary necrosis, which results in the production and release of several DAMPS or damage-associated molecular pattern molecules which are potent inducers of the immune response.
Example Question #123 : Immune And Lymphatic Systems
Bone marrow chimeric mice are an invaluable tool used by immunologists to elucidate specific mechanisms of the immune response. The generation of these chimeras involve whole body irradiation to eliminate the mouse bone marrow followed by adoptive transfer of bone marrow from a donor mouse (usually transgenic).
One critical step in the successful generation of bone marrow chimeric mice involves the depletion of T cells from the donor bone marrow. Which of the following is reason for this necessary step?
The donor T cells are unable to reconstitute, proliferate, and mature in the recipient mouse.
All of these
The donor T cells may be activated by the MHC antigens from the recipient's cells, resulting in a graft versus host response.
The donor T cells have an inherently reduced cytotoxic killing ability.
The donor T cells are inherently defective in their ability to produce cytokines and growth factors needed in the bone marrow reconstitution.
The donor T cells may be activated by the MHC antigens from the recipient's cells, resulting in a graft versus host response.
T cells from the donor must be depleted due to the risk of incompatible MHC antigens on the recipient cells. If there is incompatibility, the donor T cells will attack and kill the host cells resulting in a graft versus host response.
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