ELIMINATION OF SOLUBLE I-123 LABELED AGGREGATES OF IGG IN PATIENTS WITH SYSTEMIC LUPUS-ERYTHEMATOSUS - EFFECT OF SERUM IGG AND NUMBERS OF ERYTHROCYTE COMPLEMENT RECEPTOR TYPE-1

Using soluble I-123-labeled aggregates of human IgG (I-123-AHIgG) as a probe, we examined the function of the mononuclear phagocyte system in 22 patients with systemic lupus erythematosus (SLE) and 12 healthy controls. In SLE patients, a decreased number of erythrocyte complement receptor type 1 was associated with less binding of I-123-AHIgG to erythrocytes and a faster initial rate of elimination of I-123-AHIgG (mean +/- SEM half-maximal clearance time 5.23 +/- 0.2 minutes, versus 6.58 +/- 0.2 minutes in the controls), with possible spillover of the material outside the mononuclear phagocyte system of the liver and spleen. However, multiple regression analysis showed that serum concentrations of IgG were the most important factor predicting the rate of I-123-AHIgG elimination. IgG concentration may thus reflect immune complex clearance, which in turn, would influence the inflammatory reaction, in SLE.