What type of selection is self-tolerance developed by?

What type of selection is self-tolerance developed by?

• A. Positive selection
• B. Negative selection
• C. Clonal selection
• D. Maturation selection

Answer: (B)

Self-tolerance is primarily developed through a process known as negative selection. This process occurs during the maturation of T cells and B cells in the thymus and bone marrow, respectively. During negative selection, lymphocytes that recognize self-antigens with high affinity are induced to undergo apoptosis, or programmed cell death. This mechanism is crucial as it helps prevent autoimmunity by eliminating those immune cells that could potentially attack the body’s own tissues.

In contrast, positive selection serves to ensure that lymphocytes can successfully bind to Major Histocompatibility Complex (MHC) molecules, which is essential for their function. Clonal selection refers to the process where specific lymphocytes proliferate in response to an antigen, while maturation selection does not specifically apply to the context of self-tolerance. Thus, negative selection is directly responsible for establishing the immune system's ability to differentiate between self and non-self, thereby maintaining self-tolerance.