On the persistence of complement fixing antibodies in the serum of rabbits immunized with purified proteins

Abstract

This report is based on two experiments: Rabbit A was immunized intravenously with edestin and Rabbit B, intraperitoneally with phaseolin. Rabbit A received the first injection of protein November 15, 1920, and the last, eight days later. The quantities injected were 50, 75, 100, 125 and 150 mgm.—a total of 0.5 gm. Rabbit B received its injections between December 28, 1920, and January 5, 1921; the quantities were 100, 150, 200, 250 and 300 mgm. of protein—a total of 1 gm. The sera of these rabbits were examined from time to time for the presence of specific complement fixing antibodies, the last examination having been made on May 5, 1921. The results showed a gradual decrease in the number of antibodies. A sufficient number of these bodies, however, were present during the May determination to merit the designation of 3 plus (+ + +) with the usual complement fixation technique.

The case of Rabbit A, immunized with 0.5 gm. of protein showing in its blood the presence of complement fixing antibodies five months after immunization, is of significance inasmuch as it revives the old disputed question as to the nature of the complement fixing antibody. The widely accepted view that this antibody is an indication of the presence of an active antigenic manifestation in the body as differentiated from the agglutinin, for example, which is a true antibody, is brought to question; since one would have to assume that some of this small quantity of protein is present in the animal in some form, after 5 months—a quite unlikely condition.