Cytotoxic T Lymphocytes.

The article offers information about cytotoxic T lymphocytes (CTL). It refers to T cells that, upon contact with antigen-bearing cells, directly kill target cells which are usually infected with virus. Thus, it plays an important role in host defense against pathogens, detect and destroy tumor cells, and contribute to immune-mediated pathology in hypersensitivity reactions and autoimmune disease. The characteristics and preclinical relevance of CTL are discussed. Guidelines regulating CTL activity testing are listed.