Suppression of Fc Receptor and C4.C3 receptors of the granulocytes from patients with systemic lupus erythematosus.

The suppressive functions of Fc receptor and complement (C4.C3) receptors were studied in the granulocytes from patients with systemic lupus erythematosus (SLE). The inhibition of complement receptors was mainly due to immune complex bearing C4 or C3 fragments and to complement fragments in part, because 1. the inhibitory activity was present mostly in macromolecular fraction of SLE serum on gel filtration, and 2. the inhibitory activity was precipitated by 4% polyethylene glycol. The suppression of the complement receptors correlated with SLE disease activity.