Studies on the Toxins of Hemolytic Streptococci

Fourth Report. On the Immunological Properties of the Lethal Toxin

Abstract

(1) The lethal toxin of hemolytic streptococcus has a type-speci-ficity and is able to absorb the type-specific, mouse-protective antibodies, precipitins and the greater part of agglutinins from the homolo-gous antibacterial serum.
(2) It can give a protective, active immunization and an antitoxic immunity into mice. This active immunization is type-specific.
(3) A. P. F. (acid precipitable fraction) has an antigenicity in vitro and an immunogenicity. It can absorb all precipitins, but almost no agglutinins from immune serum with this fraction, and this immune serum has no protective power against fatal infection.