Inhibition of Immune Phagocytosis of <i>Diplococcus Pneumoniae</i> by Human Neutrophiles with Antibody against Complement

Abstract

Summary Treatment of normal human blood with rabbit antibody against human complement completely blocks the phagocytosis by the neutrophiles of Diplococcus pneumoniae in the presence of its type-specific antibody. The effect is observed whether the incubation period of blood with organisms is as short as 15 min or as long as 4 hr. The addition of fresh, untreated serum to cells from treated blood does not reverse the inhibition, nor does the addition of fresh complement-containing serum in amounts 4 times that of the original serum present. Bactericidal studies indicate that antipneumococcal serum is capable of the destruction of the organism even when the complement is inactivated by anticomplement and the phagocytes appear to be inactive.