“…In addition, components exist in the plasma or serum which can markedly enhance the cellular uptake of particulate material (5)(6)(7)(8)(9). These plasma componen ts originally called "opsonins" by Wright and Douglas ( 10) have been extensively shown to play a determinant role in phagocytosis Although the importance of opsonins in phagocytic activity has been amply demonstrated, little is known about the exact nature of the opsonic system.…”