Monocyte/macrophage Fc gamma RIII, unlike Fc gamma RIII on neutrophils, is
not a phosphatidylinositol-linked protein
C Darby, P Chien, MD Rossman and AD Schreiber
Department of Medicine, University of Pennsylvania School of Medicine,
Philadelphia.
The low affinity IgG Fc receptor, Fc gamma RIII, expressed on circulating
neutrophils, natural killer (NK) cells, and tissue macrophages, is involved
in effector functions such as cytotoxicity and immune complex clearance by
these cells. While Fc gamma RIII is reported to be a phosphatidylinositol
(PI)-linked, rather than peptide- linked, protein on neutrophils and NK
cells, its membrane linkage in macrophages has not been studied. We
examined the sensitivity of Fc gamma RIII to cleavage by PI-specific
phospholipase C (PI-PLC) in cultured monocytes and alveolar tissue
macrophages and report that this receptor is not PI-linked on these cells.
We also observed normal levels of Fc gamma RIII on cultured monocytes of a
patient with paroxysmal nocturnal hemoglobinuria, a disease in which
PI-linked proteins are deficient. The results suggest that Fc gamma RIII
occurs solely in a transmembrane form in cells of the monocyte/macrophage
lineage. In addition, we studied Fc gamma RIII on a cloned NK cell line and
found it to be resistant to the effects of PI-PLC under conditions that
cleaved Fc gamma RIII on neutrophils. Taken together, our results provide
evidence for a distinct form of Fc gamma RIII that differs from the
neutrophil receptor in its structure and, possibly, in its function.
Volume 75,
Issue 12,
pp. 2396-2400,
06/15/1990
Copyright © 1990 by The American Society of Hematology
