Quantitative Studies on the Bactericidal Actions of Serum and Complement

[摘要] The bactericidal reaction, as studied with a new photometric growth assay, has been shown to parallel the hemolytic reaction in a number of respects: a stimulation by, if not an absolute requirement for, Mg ion and antibody-complement relations which can be expressed by identical equations. In a typical experiment 700–860 molecules of antibody and 1.5 × 107 molecules of complement were necessary to kill one organism, Salmonella typhosa , at the 50% end point. This amount of antibody is calculated to cover 0.03–0.7% of the bacterial cell surface. Heating at 56°C for a few minutes has been shown to decrease the bactericidal activity, particularly of weak sera, by partial destruction of antibody. Rabbit serum has an activating effect on guinea pig complement, human serum a depressing effect in the bactericidal although not in the hemolytic reaction. The relative titer of two sera is shown to vary with heating, and the species of complement used. Additional observations are presented on the Neisser-Wechsberg inhibition, and the mechanism of the bactericidal effect.

[学科分类] 生物科学（综合）