Complex sentence: Specifically, MHC Class I genes express foreign proteins on the surface of cells that are infected by intracellular pathogens; since each T-cell has its own unique MHC receptor, Cytotoxic T-lymphocytes may bind to the MHC-antigen complex and activate it.
Split into simpler sentences: Specifically, MHC Class I genes express foreign proteins on the surface of cells that are infected by intracellular pathogens. Since each T-cell has its own unique MHC receptor, Cytotoxic T-lymphocytes may bind to the MHC-antigen complex and activate it.