Institut Pasteur, 75724 Paris Cedex 15
A component of the specific host immune response to tumor cells and to intracellular infectious pathogens (including viruses, bacteria and parasites) is the cytotoxic T lymphocytes (CTL) that kill cells expressing major histocompatibility complex-associated peptide antigens derived from the pathogen. CTL responses are critical in settings of intracellular infections. During the past three decades many laboratories have studied the role of these CTL activities mainly with a chromium release assay that measure the degree of lysis of target cells by CTL. During recent years alternative techniques have been developed. These are based on the detection of specific cytokines secreted by CTL after specific activation (Elispot assay, intracellular staining) or by the surface expression of a specific T-cell receptor (tetramers). These techniques measure different properties or function of the antigen-specific T cell activities. In this article, the principles and main characteristic of these assays are presented.