Flow cytometric determination of cytokines in activated murine T helper lymphocytes: Expression of interleukin-10 in interferon-γ and in interleukin-4-expressing cells

In an immune response, effector functions are controlled by T helper (Th) 1 cytokines [interferon-γ (IFN-γ), interleukin (IL)-2 and tumor necrosis factor-β] and Th 2 cytokines (IL-4, IL-5 and IL-10). Here we analyze by multiparameter immunofluorescence to what extent IL-2, IL-4, IL-5, IL-10 and IFN-γ are co-expressed in individual normal murine Th cells upon activation in vitro with the bacterial superantigen Staphylococcus aureus enterotoxin B, presented in the context of major histocompatibility complex class II. IL-2 and IFN-γ are co-expressed by some, but not by other Th cells. Expression of IL-4 and IFN-γ is exclusive. IL-10 is co-expressed in individual cells either with IL-4 or with IFN-γ. No IL-5-expressing cells are detected. While IL-10- and IL-4-co-expressing Th cells correspond to classical Th 2 cells, cells co-expressing IL-10 and IFN-γ could be involved in negative-feedback regulation of a Th 1 response. Apart from such functional implications, our results show that IL-2, IL-4, IL-5, IL-10 and IFN-γ are expressed independently of each other in individual murine Th cells.