Isolation and partial chemical characterization of the IgG Fc receptor of human T lymphocytes and production of an antiserum.

We report here the isolation of an IgG Fc receptor from normal human T lymphocytes. The purified receptor has a nonreduced and a reduced component of molecular weights 120,000 and 60,000, respectively, and it was functionally active in the in vitro blocking of rosette formation between T lymphocytes and IgG-coated ox erythrocytes. An antiserum raised to the Fc receptor and an isolated F(ab')2 fragment of this antiserum, also blocked rosette formation between T cells and IgG-coated ox erythrocytes. In contrast, rosette formation between T lymphocytes and IgM-coated ox or sheep erythrocytes was not blocked by the F(ab')2 fragment, demonstrating the marked specificity of this antiserum for the IgG Fc receptor. In addition, this antiserum did not block the Fc receptors of non-T cells, indicating that the T-cell IgG Fc receptor has unique antigenic determinants not shared with B cells.