Cytotoxic T lymphocytes (CTLs):

Cytotoxic CD8 T cells recognize peptides derived from antigens synthesized within the cell when presented by MHC class I molecules. This mechanism allows presentation of peptides derived from viruses. Also Know: Cytotoxic (cytolytic) T lymphocytes are also specific effectors of the cellular immune response, paicularly against virus-infected cells. In this example, a virus (e.g., influenza virus) is inhaled and infects a cell of the respiratory tract. Viral envelope glycoproteins appear on the surface of the infected cell in association with class I MHC proteins. A cytotoxic T cell binds its antigen-specific receptor to the viral antigen-class I MHC protein complex and is stimulated to grow into a clone of cells by interleukin-2 produced by helper T cells. These cytotoxic T cells specifically kill influenza virus-infected cells (and not cells infected by other viruses) by recognizing viral antigen-class I MHC protein complexes on the cell surface and releasing perforins that destroy the membrane of the infected cell. Ref: Levinson W. (2012). Chapter 57. Immunity. In W. Levinson (Ed), Review of Medical Microbiology & Immunology, 12e.