Binding of immunoglobulin- and complement-coated erythrocytes to human neutrophil subpopulations

Human neutrophils are separable into two populations on the basis of the presence or absence of Fc receptors as detected by rosette assays with IgG antibody-sensitized human erythrocytes. In the present report it was shown that IgG-sensitized sheep erythrocytes could detect some Fc receptor activity on those cells which are Fc receptor-negative with the human cell assay. There was clearly a difference between Fc receptor expressed on the positive and negative cells. Neutrophils with "high" and "low" density Fc receptor activity were studied for a range of membrane receptors for complement fragments including, C4b, C3b, C3d, and C3bi. No difference was found between the two populations of cells in their expression of complement receptors. Moreover, neither population expressed receptors for C3d, suggesting that neither population was a high proportion of immature neutrophils.