TOPICS: CD8+ cytotoxic T cells (Tc), major histocompatibility complex (MHC) class I, perforins, granzymes, apoptosis, Fas ligand (FasL), Fas, natural killer (NK) cells, antibody-dependent cell-mediated cytotoxicity (ADCC), pathogen killing by natural killer cells, IFN alpha, IFN beta, IL-2, IL-12, IFN gamma, CD56, CD16 (Fc receptor), IgG