ANTISTREPTOCOCCUS SERUM

In the protection of the animal body against virulent streptococci two factors are known to be of importance. The bacteria are first acted on by opsonin, which is found especially in the blood-serum, and thus prepared for phagocytosis by the leukocytes in which they are destroyed. The normal body usually possesses sufficient antistreptococcic power for its protection against streptococci as they occur on the mucous membranes, tonsils, etc. If the normal resistance is lowered, or an unusual number or highly virulent bacteria gain entrance to the body through some defect in the protective mechanism, the bacteria may multiply and produce disease. When such an infection runs a favorable course the streptococci stimulate the body cells to produce immune opsonin which in turn acts on the streptococci and prepares them for phagocytosis and destruction by the leukocytes. A coincident increase of leukocytes also heightens the power of the body to destroy