Distribution and properties of Fc receptors for IgG on different leucocyte populations in man.

The distribution and some characteristics of Fc receptors for immunoglobulin (Fc gamma R) were analysed on different human leucocyte populations. Interaction of Fc gamma R present on T gamma cells with ox erythrocytes-IgG immune complexes (IgG-IC) provides a switch-off signal for the expression of the Fc gamma R themselves; in addition, these receptors are sensitive to the proteolytic activity of pronase. Since both of these phenomena could have important effects on certain functional activities of the cells, we have analysed the effect of the interaction between IgG-OxE and the Fc gamma R present on various leucocyte populations. The large majority of T gamma cells or of tonsil B cells lost their Rc gamma R after interaction with IC; IC, in turn, had no effect on the Fc gamma R of AC and PMN. Twelve to 22% of the non-T, non-AC fractions retained surface Fc gamma R. Enzymatic treatment of the cells showed that T cells, non-T, non-AC and B cells have Fc gamma R sensitive to pronase, whereas Fc gamma R present on AC and PMN are resistant even to very high concentrations of the enzyme.