Maturation-linked expression of the Fc (IgG) receptor on developing human bone marrow and peripheral blood granulocytes.

Expression of Fc(IgG) receptors, as demonstrated by IgG-coated ox cells and heat-aggregated IgG, was assessed on normal human peripheral blood and bone marrow neutrophils and their precursors. The results indicate that Fc receptor development is confined to post-mitotic granulocytes, being primarily associated with neutrophil segmentation. Fc receptors were not detected on myeloblasts or promyelocytes. A mean value of 79% and 99% Fc positive segmented neutrophils were found in bone marrow and peripheral blood respectively. This highly significant difference (P less than 0.001) appears to represent a morphologically indistinguishable terminal maturation stage. Inhibition studies with IgG show that the neutrophil Fc receptor is inhibited by aggregated but not, in contrast to the corresponding monocyte receptor, by monomeric (7S) IgG. Applications of these findings to the in vivo function of the neutrophil in health and pathology are discussed.