The expression of Fcγ receptor II (FcγRII) and FcγRIII on monocytes in peripheral blood and the clearance of immunoglobulin (Ig)G-sensitized erythrocytes (EA) by tissue macrophages were investigated in parallel in patients with systemic lupus erythematosus (SLE). The relationship between receptor expression and the rate of clearance of EA (half-time) was analyzed. The detected decrease in mean fluorescence intensity of both FcRγII and FcγRIII of patients' monocytes stained with specific monoclonal antibodies (IV.3 and 3G8) was inversely correlated with the prolonged clearance half- time of 51Cr-labelled and anti-D IgG-sensitized autologous erythrocytes in these patients. A correlation was found between the impaired clearance function and the severity of the disease manifestation expressed by either clinical activity or renal involvement in our SLE patients. From these results it can be concluded that the in-vitro determination of monocyte FcγRII and FcγRIII expression may predict the in-vivo macrophage function via the same Fc receptors.
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