T cell precursors that exit the bone marrow undergo positive and negative selection in the thymus before emerging as mature T cells. These processes are controlled by cellular interactions of the thymocyte with stromal cells in the thymus. The following statements are made regarding the selection process:

A. The selection process involves negative selection of auto-reactive cells in the cortex followed by their migration to the medulla.
B. The selection process relies on the transcription factor ‘Aire’.
C. The selection process can lead to the generation of CD4 cells that can interact with dendritic cells (DCs) as well as B cells.
D. The selection process can lead to the generation of regulatory CD4 T cells.

Which one of the following options represents the combination of all correct answers?

Correct option is C

EXPLANATION-

Statement A-"The selection process involves negative selection of auto-reactive cells in the cortex followed by their migration to the medulla."
This statement is incorrect. Negative selection primarily occurs in the medulla, not the cortex. The cortex is primarily the site of positive selection.

Statement B- "The selection process relies on the transcription factor 'Aire'."
This statement is correct. The transcription factor AIRE (Autoimmune Regulator) is crucial for negative selection in the medulla by promoting the expression of peripheral tissue antigens.

Statement C- "The selection process can lead to the generation of CD4 cells that can interact with dendritic cells (DCs) as well as B cells."
This statement is correct. Mature CD4+ T cells help both dendritic cells and B cells in immune responses.

Statement D- "The selection process can lead to the generation of regulatory CD4 T cells."
This statement is correct. Some CD4+ T cells differentiate into regulatory T cells (Tregs) during selection, especially influenced by signals during negative selection.

So, the correct option is (c) - B, C and D.