IMMUNOLOGY

Detailed explanation-1: -There are two main structurally and functionally distinct classes of MHC proteins: class I MHC proteins, which present foreign peptides to cytotoxic T cells, and class II MHC proteins, which present foreign peptides to helper cells (Figure 24-48).

Detailed explanation-2: -Major histocompatibility complex (MHC) antigens bind peptides of diverse sequences with high affinity. They do this in order to generate maximal immunological protection by covering the spectrum of peptides that may be seen by a host over the course of its lifetime.