Opsonins Distinct From Other Antibodies

Abstract

Wright and Douglas first demonstrated that normal serum contains certain substances, called by them opsonins, which render various bacteria suceptible to phagocytosis by polynuclear leucocytes. Wright and his followers, Neufeld and Rimpau, as well as others have shown that the substances arising in response to immunization promote phagocytosis by a similar opsonic action upon the bodies that are taken up by the phagocytes.1 Whether this opsonic action is the property of antibodies with which we are already somewhat familiar, such as amboceptors and agglutinins, or whether opsonins are distinct and independent units in the serum, is an interesting and important question. Before the exact interaction of serum and cells in phagocytosis had been made clear, Metchnikoff and his followers attributed the promotion of phagocytosis by immune serum to the so-called fixators, which in general are regarded as identical with Ehrlich's amboceptors. Quite recently Dean,2 from the results of the study of the effects of heat upon the opsonic power of normal and immune serum, has expressed the view that amboceptors may exercise the functions of opsonins, which consequently cannot be regarded as independent substances. Neufeld and Topfer,3 however, as well as Barratt,4 hold that the opsonic substances for erythrocytes? hemopsonins?that arise in animals on immunization with alien blood are distinct from the hemolytic amboceptors, because a serum might be lytic for certain corpuscles without being opsonic, and vice versa. In the course of our work a number of facts have been brought out that seem to be of importance in regard to the question of the entity of the opsonins. * Received for publication March 25, 1906.