Major histocompatibility complexes (MHCs) are presented to different T cells to identify the antigen on the host or infected cell. There are two MHCs - class I and class II. The class I MHC presents to cytotoxic T cells while MHC II to helper T cells.
A cytotoxic T cell only binds to the infected cell displays the foreign antigen such as viruses on the infected cell surface in order to recognize and kill the cells.
