Developmentally ordered appearance of a functional Fc gamma receptor on TCR V gamma 3 thymocytes. Evidence for stimulation-induced expression.

Abstract

In the present report, we show that the Fc gamma receptor (Fc gamma R) becomes expressed on mature TCR V gamma 3 thymocytes, but it is absent on immature TCR V gamma 3 cells. Both Fc gamma RIII are Fc gamma RIII are expressed. The in vivo expression of the Fc gamma R on mature TCR V gamma 3 thymocytes coincides with an activated phenotype of the cells. In vitro, anti-CD3 stimulation of Fc gamma R-negative, immature TCR V gamma 3 thymocytes results in the expression of the Fc gamma R. The Fc gamma R of short-term IL-2-cultured, mature TCR V gamma 3 thymocytes is functional in an Ab-mediated cytotoxicity assay. In addition, it is shown that cross-linking of the Fc gamma R induces an increase in cytoplasmic Ca2+. Collectively, our findings show that mature TCR V gamma 3 thymocytes express a functional Fc gamma R; evidence is presented that this could be a result of in vivo activation of these cells.