Cytotoxic T Cells

Abstract

Cytotoxic T lymphocytes (CTLs) represent one of several types of cells of the immune system that have the capacity to directly kill other cells. They play a major role in host defense against viral infection, as well as infection by other intracellular pathogens that replicate in the cytoplasm of the host cell. Clinically important infections in which CTLs are regarded as a vital defense mechanism include human immunodeficiency virus (HIV)-1 (Carmichael et al. 1993; Koup et al. 1991), cytomegalovirus (Riddell et al. 1992), influenza (McMichael et al. 1983), hepatitis B (Bertoletti et al. 1994; Penna et al. 1991), and malaria (Hill et al. 1992). CTLs are also recognized as critical components of antitumor immunity (Roth et al. 1994). Due to the important functions that CTLs play in the immune system, assays of CTL activity have become an integral component of immunotoxicity assessment. This chapter will review the understanding of CTL development and functions, methods for assessing CTL functions, and the mechanisms by which drugs and other xenobiotic chemicals suppress CTL activity.