Immune-complex phagocytosis by human polymorphonuclear granulocytes.

A new two-step centrifugation technique is described for the rapid preparation of viable pure polymorphonuclear granulocytes from 9.5 ml of venous blood. The phagocytosis of these cells was stimulated by soluble DNA-anti-DNA complexes, produced in vitro by incubating high mol. wt. DNA with sera obtained from patients with severe SLE. The measure of phagocytosis was the amount of nitroblue-tetrazolium (NBT), reduced by the active microphages. The reduced NBT was estimated by counting the formazane positive cells or by extracting and measuring it spectrophotometrically. The immune-complex phagocytosis of control human granulocytes showed a linear relationship with the cell count per reaction mixture and displayed a bell-shaped dose-response curve as function of the immune-complex. The immune-complex phagocytosis by SLE granulocytes was decreased by about 40 per cent as compared to normal granulocytes.