Question

In T-cell tolerance, positive selection is associated with:

A. presentation of self-antigens to the T cell
B. production of a large number of B cells
C. deletion of self-reactive T cells
D. MHC restriction of T cell repertoire

Answer 1

Positive selection in T-cell tolerance is associated with MHC restriction of T cell repertoire, ensuring that T cells can recognize antigens when presented by MHC molecules without reacting to self-antigens.

Step-by-step explanation:

The positive selection in T-cell tolerance is associated with D. MHC restriction of T cell repertoire. This process ensures that developing T cells in the thymus that bind with self-MHC molecules, but not necessarily to self-antigens, continue to mature, allowing them to recognize foreign antigens when presented by these molecules.

During T-cell development in the thymus, thymocytes express both CD4 and CD8 receptors and are tested for their ability to bind MHC molecules. This is known as positive selection, which is crucial for the proper function of T cells within the immune system. It allows for the selection of T cells that have the capability to recognize antigens presented by the MHC molecules of the body. Only the T cells that can interact with these MHC molecules are allowed to proceed further in their maturation; those that do not bind appropriately are removed by apoptosis, ensuring that the T cells are MHC-restricted and capable of identifying foreign, but not self, antigens.