Phagocytosis-connected oxygen consumption by peripheral leukocytes from patients with systemic lupus erythematosus

The phagocytic activity of peripheral blood leukocytes was assayed by means of oxygen consumption in 28 patients with systemic lupus erythematosus (SLE) and 22 normal individuals. The method in which zymosan was added to a small volume of whole blood enabled us to assay quantitatively and rapidly both the phagocytosis-connected oxygen consumption and the opsonizing time. The degree of oxygen consumption by phagocytes from SLE patients was not significantly different from that in normals. Opsonizing time of zymosan by autologous serum in SLE patients did not differ from that in normals either. It should be emphasized, however, that the opsonizing time of zymosan in SLE patients was inversely correlated with serum complement level, especially C3 level (coefficient of correlation = -0.76, p less than 0.001). This raises the possibility that the phagocytosis may be delayed in SLE patients with low titers of C3.