ON THE MECHANISM OF OPSONIN AND BACTERIOTROPIN ACTION : I. CORRELATION BETWEEN CHANGES IN BACTERIAL SURFACE PROPERTIES AND IN PHAGOCYTOSIS CAUSED BY SERA OF ANIMALS UNDER IMMUNIZATION.

Methods are described for investigating the relation between phagocytosis of bacteria by polymorphonuclear leucocytes, and certain physical-chemical properties of the bacterial surface. Serum sensitization causes the following changes in the properties of acid-fast bacteria: (a) increased cohesiveness, (b) decrease in surface electric potential difference, (c) decrease in wettability of the bacteria by oil, and (d) increased phagocytosis. Tests have been conducted periodically with the sera of 4 rabbits under active immunization with as many strains of acid-fast bacteria; the parallelism between the alteration in bacterial surface properties and the promotion of phagocytosis by these sera has been, within the experimental error, complete. The percentage of phagocytosis of a given bacterial suspension has been found to depend both upon the sensitizing serum component or components deposited upon the bacterium and upon the intrinsic properties of the unsensitized bacterial surface.