Kinetics of monocyte receptor activity for immunoproteins in patients with sarcoidosis

Peripheral blood monocytes from patients with active sarcoidosis have increased ability to bind IgG-antibody-coated and C3-coated erythrocytes. Binding of monocytes from sarcoid patients is inhibited less than for normals with IgG1 and IgG3 in the fluid phase. Following phagocytosis of latex particles, monocytes from sarcoides patients retain the capacity to bind IgG-coated erythrocytes, whereas monocytes from normal individuals show disappearance of IgG receptors followed by recovery during a 6-8 hr period. Preliminary studies (8 patients) of monocytes from patients with Crohn's disease show some increase in binding of IgG-coated erythrocytes as compared with normals; this increase, however, is less than for sarcoidosis patients. Preliminary experiments with multistranded polynucleotides (poly I:C:U) show increased activity for normal monocytes and no detectable effect on IgG receptor activity for sarcoid monocytes. Thus peripheral blood monocytes of patients with sarcoidosis have increased IgG and C3 receptors sites, suggesting activation of monocytes in this disease and perhaps in other granulomatous disorders.