Monocyte IgG receptor activity, dynamics, and modulation-normal individuals and patients with granulomatous diseases.

Studies of monocyte IgG receptor activity by tritration of rabbit Forssman antibody and fluid phase inhibition with human IgG1 and IgG3 indicate increased activity for cells from patients with sarcoidosis in comparison to normal individuals. IgG receptor activity was also increased for cells from patients with tuberculosis and, to some degree, for Crohn's disease patients. Monocyte C3 receptor activity is increased in sarcoidosis and Crohn's disease. Following phagocytosis of latex particles, IgG receptor activity remains for monocytes from sarcoidosis patients, whereas activity transiently disappears for monocytes from normal individuals. Incubation with multistranded polynucleotides increases IgG receptor activity for normal subjects and has no significant effect on cells from patients with sarcoidosis or Crohn's disease. The findings suggest that circulating monocytes from patients with sarcoidosis, Crohn's disease, and tuberculosis are activated in vivo as reflected by increased IgG and C3 receptor activity.