Expression of the Fc receptor for IgG (Fc gamma RII/CDw32) by human circulating T and B lymphocytes.

Tissue-specific isoforms of the human FcR for IgG Fc gamma RII (CDw32) have previously been described by using mAb. These mAb were shown to exhibit different patterns of reactivity with lymphocytes. Among human PBL, Fc gamma RII has been detected on B cells but not T cells when assessed by flow cytometry and microscopy with the use of mAb KB61 and 41H16. Although KB61 and 41H16 were found to react with B cells, the mAb IV.3, CIKM5, and 2E1 did not react with any PBL subset. In this study, we show that KB61 and 41H16 react strongly with the majority (93-96%) of B cells (CD20+), and weakly with a proportion (18-42%) of T cells (CD3+), including 10 to 14% of CD4+ and 27 to 69% of CD8+ cells. In addition, mRNA for Fc gamma RII was detected in purified CD3+CD8high+ lymphocytes by polymerase chain reaction. KB61 and 41H16 also reacted with a majority of CD3-CD16/CD56+ cells, and CD3-CD20- cells. These findings indicate that a subset of T cells and non-T/non-B cells express Fc gamma RII, and are of interest in the light of previous studies which postulate that human Fc gamma R+ cells and Fc gamma RII+ murine T cells suppress the B cell immune response.