Binding characteristics of Fc receptors for IgG on human peripheral blood Tγ lymphocytes and “L” lymphocytes: A technical report

Abstract

The binding capacity of Fc receptors for IgG on human blood T (E-rosette forming) cells has been compared with non-T cells (B cells and “L” cells) by several EA-rosette methods and immunofluorescence. It has been established previously that B cells possess low avidity (or density) Fc-IgG receptors that can be detected by rosette formation with sensitized bovine RBC. L cells, the C3 receptor negative subset of non-T, non-B cells possess high avidity (or density) Fc-IgG receptors detected by human red blood cells (RBC) sensitized with Ripley anti-CD serum and these cells have the capacity to bind small aggregates of IgG at 4°C. Using several double marker techniques which included a “Ripley-equivalent” EA-rosette procedure, we have shown that 7% of freshly prepared blood lymphocytes possess both receptors for sheep RBC and high avidity Fc-IgG receptors indistinguishable from those on L cells. Approximately one-third of lymphocytes with high avidity Fc-IgG receptors in unseparated preparations were Tγ cells. Paired studies on unseparated and purified T lymphocytes revealed that after the E-rosette procedure an additional 7 to 14% of lymphocytes with low avidity Fc-IgG receptors appeared. Fc receptors on this subset were detected only by sensitized bovine RBC. Approximately 3% of blood lymphocytes possess neither E, Ig, or Fc receptors. These studies have shown that Fc receptors on Tγ cells can have heterogeneous binding avidities and that the expression and avidity of Fc-IgG receptors on Tγ cells is affected by the technical manipulation of these cells.