Final answer:
The most important signals for differentiation of naïve CD4+ T cells into distinct subsets are the molecules CD4 and CD8.
Step-by-step explanation:
The most important signals for differentiation of naïve CD4+ T cells into distinct subsets are the molecules CD4 and CD8. Naïve CD4+ cells bind to antigen-presenting cells (APCs) via their antigen-embedded MHC II molecules and are stimulated to become helper T (TH) lymphocytes, while CD8+ cells engage antigen-embedded MHC I molecules on APCs and are stimulated to become cytotoxic T lymphocytes (CTLs). These molecules regulate how T cells will interact with and respond to APCs, and the different subsets of T cells play different roles in the immune system.