Antibody Formation* I. the Suppression of Antibody Formation by Passively Administered Antibody Bx

In 1909, Theobald Smith (1) showed that injection of partially neutralized diphtheria toxin-antitoxin mixtures induced antitoxin formation in experimental animals, but that immunity did not result from mixtures containing a sufficient excess of antitoxin. These observations were subsequently confirmed (2-6) and have been extended to the study of additional antigens, such as tetanus toxoid (7-10), sheep red blood cells (11), poliomyelitis virus (12, 13), and bacteriophage (14, 15). In this paper, several factors affecting the capacity of passively administered antibody to suppress antibody production have been examined. I t has been shown that the degree of antibody suppression is largely determined by the intensity of the antigenic stimulation and the dissociation of the specific complex in vivo. I t has also been found that antibody injected several days after immunization can prevent a primary antibody response in guinea pigs. I t is suggested, therefore, that serum antibody may play a role in the regulation of antibody formation.