Intracellular staining for TNF and IFN-gamma detects different frequenciesof antigen-specific CD8(+) T cells

CD8(+) T lymphocytes are important mediators of adaptive immunity against c ertain viral, protozoan and bacterial pathogens. Activated CD8(+) T cells a re able to induce cytolysis of infected cells (perforin and CD95-CD95L medi ated pathways) and also elaborate cytokines, including IFN-gamma and TNF af ter appropriate MHC class I-peptide recognition. New technologies for the d etection of antigen-specific CD8(+) T cells, including tetrameric MHC class I-peptide complexes, intracellular IFN-gamma staining and IFN-gamma ELISPO T analysis have revised our understanding of the magnitude of the CD8(+) T cell response to infection. Here, using intracellular cytokine staining, we compare detection of IFN-gamma and TNF in the analysis of pathogen-specifi c CD8+ T cell lines and CD8(+) T cells after primary viral infection (LCMV) or secondary bacterial infection (Listeria monocytogenes). Under multiple conditions and with multiple epitopes, we find that staining for intracellu lar IFN-gamma consistently detects a higher frequency of antigen-specific C D8(+) T cells than detection of intracellular TNF. However, (a) intracellul ar staining for TNF can be used to detect antigen-specific CD8(+) T cell re sponses and (b) intracellular staining for cytokines is a useful approach f or in vitro characterization of antigen-specific CD8(+) T cell lines. (C) 2 000 Elsevier Science B.V. All rights reserved.