CD4+CD8dim T cells represent a minor subset of the total CD3+ T cell population in peripheral blood. Although transient and persistent expansions of these cells have been reported in both healthy and diseased individuals, the functional properties of the CD4+CD8dim population are largely unknown. In this study, we examined antigen-specific cytokine and proliferative responses of the CD4+CD8dim subset. In whole blood cultures stimulated with the viral antigens HCMV and HIV-1, a significant fraction of the CD4+CD8dim subset exhibited cytokine expression and proliferation in response to antigen activation. Typically, the CD4+CD8dim population contained two- to eightfold higher frequencies of antigen-specific cytokine producing cells than the CD4+CD8- population. Phenotypic analysis of the cytokine expressing CD4+CD8dim population indicated that these cells are memory T cells, with a high frequency of this population expressing the cytotoxic markers CD56 and perforin. Furthermore, the CD4+CD8dim cytokine responses to CMV were shown to be MHC class II dependent. Significantly, purified CD4+CD8dim T cells were found to possess higher CMV-specific cytotoxic activity than purified CD4+CD8- T cells in a standard 51Cr-release CTL assay. Thus, CD4+CD8dim T cells appear to be MHC class II dependent, are capable of cytolytic effector activity, and are highly enriched within the CD4+ cell populations specific for HCMV and HIV-1.
|Original language||English (US)|
|Number of pages||9|
|Journal||European Journal of Immunology|
|State||Published - Sep 6 2001|
- Flow cytometry
ASJC Scopus subject areas
- Immunology and Allergy