Open AccessEnumeration of Cytotoxic CD8 T Cells Ex Vivo during the Response toListeria monocytogenesInfection
Author(s) -
Dietmar M. Zaiss,
Alice J.A.M. Sijts,
Tim R. Mosmann
Publication year - 2008
Publication title -
infection and immunity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.508
H-Index - 220
eISSN - 1070-6313
pISSN - 0019-9567
DOI - 10.1128/iai.00563-08
Subject(s) - cytotoxic t cell , biology , cd8 , ex vivo , antigen , immune system , interferon gamma , interleukin 21 , immunology , antigen presenting cell , t cell , microbiology and biotechnology , in vivo , in vitro , biochemistry
Cytotoxicity is a key effector function of CD8 T cells. However, what proportion of antigen-specific CD8 T cells in vivo exert cytotoxic activity during a functional CD8 T-cell response to infection still remains unknown. We used the Lysispot assay to directly enumerate cytotoxic CD8 T cells from the spleen ex vivo during the immune response to infection with the intracellular bacteriumListeria monocytogenes . We demonstrate that not all antigen-responsive gamma interferon (IFN-γ)-secreting T cells display cytotoxic activity. Most CD8 T cells detected at early time points of the response were cytotoxic. This percentage continuously declined during both the expansion and contraction phases to about 50% at the peak and to <10% of IFN-γ-producing cells in the memory phase. As described for clonal expansion, this elaboration of a program of differentiation after an initial stimulus was not affected by antigen or CD4 help but, like proliferation, could be influenced by later reinfection. These data indicate that cytotoxic effector function during the response to infection is regulated independently from IFN-γ secretion or expansion or contraction of the overall CD8 T-cell response.