Immunological studies of peripheral blood monocytes in patients with systemic lupus erythematosus. Part 2. Monocyte Fc receptor functions.

Monocyte Fc receptor(Fc R) functions were studies in patients with systemic lupus erythematosus(SLE) by examining rosette formation and phagocytosis of monocytes using anti-Rh antibody coated red blood cells(EA). The rosette index(R.I.), which is an expression of the average number of EA attached to a monocyte surface, was significantly higher with SLE monocytes than with normal controls. In contrast, the phagocytosis index (P.I.), which is an expression of the average number of EA phagocytosed by a monocyte, was significantly lower. Kinetic studies revealed that between active SLE and control monocytes, there were no differences in EA kinetics after EA had attached to the monocyte surface membrane. A close correlation was obtained between the R.I. values and the concentration of gammaglobulins (R=0.69). A negative correlation was found between the R.I. values and the levels of serum complement (CH(50): R=-0.65, C(3): R=-0.62, C(4): R=-0.49). There were no significant correlations among the R.I. values and the levels of circulating immune complexes, the grade of hematuria, the degree of proteinuria and histological findings of the kidney. P.I. values did not correlate with any of these parameters. These results suggest that Fc R functions of peripheral blood monocytes are increased in patients with SLE and are closely related to disease activity