The bactericidal action of typhoid antibody.

THE study of the bactericidal action of serum on bacteria has progressed slowly, partly because of the complex nature of serum, in which there are several antibacterial mechanisms, and partly because of misleading results due to the methods of study employed. The present work was undertaken to consider only one bactericidal system, that of antibody and complement, with the object of measuring the bactericidal action of antibody on Salmonella typhi. When normal antibody is under consideration it is especially difficult to be certain that only a single reaction is being observed because relatively concentrated serum has to be employed. With immune antibody much greater dilution of the serum is possible so that confusion is unlikely to be produced by such serum constituents as properdin (Pillemer, Blum, Lepow, Ross, Todd and Wardlaw, necessary unless a strain is being examined for the first time. Sterility controls are omitted, since contaminants are obvious from the appearances they produce.