Cytotoxic T cells can respond only to cells that display abnormal MHC Class II molecules.

Cytotoxic T cells primarily respond to cells displaying abnormal peptides bound to MHC Class I molecules, not Class II. MHC Class I molecules are found on almost all nucleated cells and present endogenous antigens, while MHC Class II molecules are typically found on professional antigen-presenting cells and present exogenous antigens.