Complement and Opsonic Activities of Fresh Human Sera

Abstract Previous work from this laboratory (1) confirmed earlier observations that there is a thermolabile anti-staphylococcus opsonin in fresh guinea pig serum which operates as a function of its concentration; and that an inactivated antistaphylococcal rabbit serum also behaves as an opsonin. The latter gives a zone effect. It was also noted that there is practically no spontaneous phagocytosis of staphylococci by human leucocytes in the absence of an opsonic agent. In a second paper of the same series dealing with the opsonic power of different mammalian sera (2), the opsonic power of each serum was evaluated with respect to its over-all complement titer, and the conclusion was drawn that “no relationship exists between the hemolytic complementary and opsonic powers of the guinea pig, human, monkey (rhesus), dog, cat and sheep sera toward staphylococci.”