Cytotoxic T lymphocytes (CTLs):: (A) Recognize the same antigens as CD4 T cells, (B) Secrete cytokines that stimulate the differentiation and proliferation of B cells, (C) Are impoant in the control of viral infections, (D) Most often recognize antigens that have been phagocytosed, degraded, and presented on the surface of an APC
Answer is C. 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.