Question

What does positive selection in the thymus refer to?

a) Recognition of MHC class I and II by double-positive thymocytes.
b) Recognition of MHC class I and II by single-positive thymocytes.
c) Acquiring a nascent TCR by precursor T cells.
d) Apoptosis of double-positive thymocytes.
e) Recognition of MHC class I or II by single-positive thymocytes.

Answer 1

Positive selection in the thymus refers to the recognition of MHC class I and II by single-positive thymocytes. It helps in the selection and maturation of T cells in the thymus.

Step-by-step explanation:

Positive selection in the thymus refers to the recognition of MHC class I and II by single-positive thymocytes. Thymocytes that can interact appropriately with MHC molecules receive a positive stimulation that moves them further through the process of maturation, whereas thymocytes that do not interact appropriately are not stimulated and are eliminated by apoptosis. This process helps in the selection and maturation of T cells in the thymus.