Question

Which of the following conditions may lead to the development of autoimmunity?

a. Self antigens not previously encountered by T cells are released into the circulation
b. Foreign antigens mimic self antigens
c. Cells may inappropriately display class II MHC molecules
d. Certain pathogens nonspecifically activate B cells
e. All of the above are correct

Accepted Answer

Step 1: Understand the concept of autoimmunity. Autoimmunity occurs when the immune system mistakenly targets the body's own tissues, recognizing self-antigens as foreign and initiating an immune response against them. Step 2: Analyze option (a): Self antigens not previously encountered by T cells are released into the circulation. This can lead to autoimmunity because T cells may recognize these antigens as foreign and attack them. Step 3: Analyze option (b): Foreign antigens mimic self antigens. This phenomenon, known as molecular mimicry, can cause the immune system to attack self tissues that resemble foreign antigens. Step 4: Analyze option (c): Cells may inappropriately display class II MHC molecules. Class II MHC molecules are typically displayed by antigen-presenting cells, but if other cells display them incorrectly, it can lead to the activation of T cells against self-antigens. Step 5: Analyze option (d): Certain pathogens nonspecifically activate B cells. This nonspecific activation can lead to the production of autoantibodies, which target self-antigens, contributing to autoimmunity. Finally, evaluate whether all options (a, b, c, d) are correct, as suggested by option (e).

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Concetti chiave

Autoimmunity

Molecular Mimicry

MHC Class II Molecules