Question

Which of the following processes is not dependent on an interaction involving MHC class I or class II molecules? (Select all that apply.)

a. positive selection of α:β T cells
b. intracellular signaling by pre-T-cell receptors
c. negative selection of αβ T cells
d. peripheral activation of mature naive T cells
e. positive selection of γ:δ T cells.

Answer 1

Processes not dependent on MHC interactions are the positive selection of γ:δ T cells and intracellular signaling by pre-T-cell receptors. Positive and negative selection of α:β T cells and peripheral activation of mature naive T cells are MHC dependent.

Step-by-step explanation:

The processes that are not dependent on an interaction involving MHC class I or MHC class II molecules are positive selection of γ:δ T cells (option e) and intracellular signaling by pre-T-cell receptors (option b). Positive selection of γ:δ T cells does not rely on MHC molecules because these cells recognize antigens in a different manner and do not require MHC for their selection in the thymus. Intracellular signaling by pre-T-cell receptors occurs during T cell development before the selection processes dependent on MHC presentation. Positive selection of α:β T cells (option a) and negative selection of αβ T cells (option c) both involve interactions with MHC molecules, as they ensure T cells recognize self-MHC and are not self-reactive, respectively. Peripheral activation of mature naive T cells (option d) also relies on the interaction with MHC, as mature T cells become activated upon recognizing a processed foreign antigen presented by a self-MHC molecule.