The concentration of IgG in the serum is a major determinant of Fc-
dependent reticuloendothelial function
JG Kelton, J Singer, C Rodger, J Gauldie, P Horsewood and P Dent
Defective Fc receptor-specific reticuloendothelial (RE) function has been
reported in certain patients with a variety of immunologic and
nonimmunologic diseases. The mechanism responsible for the impaired RE
function is uncertain, but it could be caused by immune complexes that are
present in many of these disorders. Alternatively, the impaired RE function
could be a secondary effect of the high concentrations of monomeric IgG in
the serum of these patients, since monomeric IgG can compete with complexed
IgG for macrophage receptors in vitro. We studied the Fc-dependent RE
function in 30 healthy control subjects and 27 patients using IgG-coated
radiolabeled autologous red cells. There was a significant relationship
between the concentration of IgG in the serum and the rate of clearance of
antibody-sensitized cells (r = 0.51, P less than .01). Patients with
hypergammaglobulinemia had the slowest Fc-dependent clearance, whereas
those with hypogammaglobulinemia had the most rapid clearance. Immune
complexes (Raji or polyethylene glycol) could not be shown to contribute to
Fc-dependent RE clearance above the effect of the IgG in the serum. The
unusually rapid clearance in a patient with hypogammaglobulinemia could be
returned to normal by raising the concentration of IgG in the serum. This
study supports the concept that serum (monomeric) IgG competes with immune
complexed IgG for macrophage Fc receptors in vivo. The competition for Fc
receptors determines the level of competence of Fc-dependent RE function.
Based on the results of this study, one can predict that a number of
disorders characterized by hypergammaglobulinemia also will have impaired
Fc-dependent RE function.
Volume 66,
Issue 3,
pp. 490-495,
09/01/1985
Copyright © 1985 by The American Society of Hematology
