The occurrence of antipneumococcus substances in the blood serum in lobar pneumonia.

Abstract

With a method1 previously described for carrying on growthinhibition tests with the pneumococcus, it was shown that a mixture of serum and leucocytes from naturally resistant animals (cats or dogs) was capable of inhibiting the growth of pneumococci in considerable numbers, whereas a serum-leucocyte mixture from a susceptible animal (rabbit) was found to have no such action. It was possible, however, to passively confer growth-inhibitory and pneumoccidal powers on serum-leucocyte mixtures of the latter animal by adding a very small quantity of a homologous antipneumococcus serum. By comparing different immune sera the degree of growth inhibition thus obtained paralleled closely their protective action for mice. In a subsequent investigation on experimental pneumococcus infection, it was found that recovery was invariably accompanied by the development in the serum of the infected animals of immune substances, which could be demonstrated by the occurrence of pneumococcus growth-inhibition when such serum w...