Transforming growth factor-beta1, a strong costimulator of rat T-cell activation promoting a shift towards a Th2-like cytokine profile

Abstract TGF-β is a known regulator of hematopoietic cells. In this study we suggest a major role of adherent spleen cells (adh-splc), to convert an inhibitory effect of TGF-β1 on T-cell activation into a stimulatory effect. We show that interaction of TGF-β1 with adh-splc induces a costimulatory effect on T-cell proliferation. This costimulatory signal requires the adh-splc to be in physical contact with the T-cells. Presence of adh-splc results in a shift towards a Th2-like response with a cytokine profile of increased IL-10 and decreased IFN-γ. In the adh-splc population the increase of IL-10 is most pronounced at start of activation, whereas in the T-lymphocyte population, IL-10 increases at the end of culture. The suppression of the IFN-γ production by TGF-β1 is shown to be an important mechanism by which TGF-β enhances proliferation of Th2 lymphocytes.