Single cell analysis of antigen-specific T cell responses in HIV-infected individuals

Antigen-specific and polyclonally induced T cell responses were analyzed in 10 HIV-infected individuals and in 14 controls by enumerating the numbers of tetanus toroid (TT)-specific and phytohemagglutinin (PHA)-induced IFN-ga mma-secreting cells (SC) and IL-4-SC using an enzyme-linked immunospot assa y. Whereas the numbers of IFN-gamma-SC in HIV-infected patients were not di fferent from those of the controls in response to an in vitro stimulation w ith PHA, they were significantly decreased in response to an in vitro stimu lation with TT, both before and after a TT booster. Cell depletion experime nts indicated that this difference was related to an impairment of CD4(+) T -cell-mediated TT-specific IFN-gamma secretion. Concerning IL-4, the number s of both polyclonally induced IL-4-SC and TT-specific IL-4-SC were signifi cantly lower in HIV-infected patients than in the controls. It is concluded that secretion of antigen-specific cytokines of both Th1 and Th2 types is depressed in HIV-infected patients. (C) 1999 Academic Press.