Maturation of adult peripheral blood CD38(+)CD4(+) T cells demonstrated by cytokine production in response to a superantigen, TSST-1.

This study looks at immunoincompetent CD4(+) T cells in adult peripheral blood (APB) using cytokine production in response to a superantigen as a measure of function. We compared the function of APB CD38(+)CD4(+) and CD38(-/low)CD4(+) T cells to that of cord blood (CB) CD4(+) T cells. APB CD4(+) T cell blasts produce substantial amounts of IL-2 in response to TSST-1 restimulation, while CB CD4(+) T cell blasts produce less. APB CD38(+)CD4(+) T cells produce low levels of IL-4 and IFN-gamma in response to TSST-1, even after activation, while APB CD38(-/low)CD4(+) T cells retain their ability to produce high levels of these cytokines despite high CD38 expression. These results suggest that the developmental stage of APB CD38(+)CD4(+) T cells lies between that of CB CD4(+) T cells and APB CD38(-/low)CD4(+) T cells and that APB CD38(+)CD45RO(-)CD4(+) T cells gradually cease to express CD38 as they acquire full function. We reconsider CD4(+) cell maturation and response to TSST-1 and discuss the implications of T cell maturity on infectious diseases.