Phagocytosis, bactericidal capacity, and PGE2 production of monocytes in systemic lupus erythematosus and rheumatoid arthritis.

Peripheral blood monocytes from 10 systemic lupus erythematosus (SLE) and 10 rheumatoid arthritis (RA) patients as well as from 24 controls were studied for such functions as phagocytosis, bactericidal capacity, iodination, and PGE2 production. Phagocytosis of opsonized erythrocytes, exploring only the Fc receptor, was increased in SLE and RA. Killing of Staphylococcus aureus was decreased in both SLE and RA in the presence of AB serum, but not in the presence of autologous serum. Iodination was, on the average, normal in SLE and elevated in RA. Prostaglandin E2 production was decreased in SLE (except with the highest concentration of Con A) and increased in RA. In SLE, functional alterations were more pronounced in clinically active than in inactive disease. These results show that in SLE and RA peripheral blood monocytes have alterations of their functions that are independent of serum factors. It is suggested that these abnormalities may be relevant to the pathogenetic mechanisms and evolution of these diseases.