Dynamics of the 19S and 7S hemolysin responses in rabbits.

The sequential appearance in immunized rabbits of 2 classes of monospecific hemolytic antibody, differing in electrophoretic mobility, molecular weight, and hemolytic efficiency, was first reported by Stelos and Talmage [11. They found that in animals given a few injections of sheep erythrocytes (SRBC) and bled shortly afterwards, all hemolytic activity occurred in the yi (IgM) serum fraction and was associated with a fast-sedimenting (19S) molecular species of high hemolytic efficiency. In sera obtained after repeated injections spaced over several months, hemolytic activity also appeared in the 72 (IgG) fractions. This antibody was slow-sedimenting (75), hemolytically inefficient, and could be demonstrated in early sera only by its antigen-binding capacity. In subsequent, related reports Bauer and Stavitsky [2] and Bauer et al. [3] stated that they were unable to demonstrate 75 antibody in rabbits injected only once with SRBC. In recent work employing the Forssman antigen, Taliaferro and Taliaferro [4] observed that in the rabbit between the first and fourth weeks after a single injection of heated horse kidney mince, 296-3(?6 of the serum hemolysin activity was due to 75 antibody. However, none of these studies focused on the dynamics of the 195 and 75 hemolysin responses, based on titers of sera obtained sequentially after primary and secondary stimulation, although these dynamics have been described for several other animal-antigen systems [3, 5-7].