PATHOLOGY

Detailed explanation-1: -MHC class II molecules at the surface of antigen presenting cells present antigenic peptides to CD4+ T helper cells. However for effective cell surface antigen presentation, a number of highly synchronized events must first take place intracellulary.

Detailed explanation-2: -Most cells in the body can present antigen to CD8+ cytotoxic T cells via MHC class I; however, the term “antigen-presenting cell” is often used specifically to describe professional APCs. Such cells express MHC class I and MHC class II molecules and can stimulate CD4+ helper T cells as well as cytotoxic T cells.

Detailed explanation-3: -The main function of major histocompatibility complex (MHC) class II molecules is to present processed antigens, which are derived primarily from exogenous sources, to CD4(+) T-lymphocytes. MHC class II molecules thereby are critical for the initiation of the antigen-specific immune response.