Immune complex clearance by monocytes and macrophages in systemic lupus erythematosus

During the last 30 years more than 700 patients with systemic lupus erythematosus (SLE) have been treated in our department with their data analyzed. Here we focus on circulating immune complex (CIC) and its clearance. We demonstrated, microscopically, that the uptake of IgG sensitized erythrocytes (EA); via monocytes, (Mo) of SLE patients, was elevated and correlated with the high CIC content. The in Vivo clearance of sensitized, autolog E, and the in vitro degradation rate of soluble IC by Mo of SLE patients were decreased. This discrepancy could be explained: by the, molecular heterogeneity of Fc gamma R being recognized lately. The high Fc gamma RI expression and the low Fc lambda RII and Fc gamma RIII expression were detected by monoclonal antibodies (mAb) on Mo in SLE. The EA bound mostly to Fc gamma RI, Fc gamma RII and, Fc gamma RIII have a role in phagoeytosis. The decreased receptor expression and function correlated with the disease activity and renal involvement. The shedding of receptors may cause a decrease on Mo surface, with the soluble FcRII I and Fc gamma RIII levels being elevated in serum of SLE patients. The mannose binding receptors, which play a role in the phagoeytosis, of apoptotic cells in SLE, were also decreased on Mo of SLE patients. (c) 2007 Published by Elsevier B.V.