Rates of Antibody Synthesis During First, Second, and Hyperimmune Responses of Rabbits to Bovine Gamma Globulin

Abstract

Knowledge of the rates of antibody synthesis throughout the immune response is of great importance in the evaluation of the various factors contributing to antibody production. Estimations of these rates have been previously possible in systems in which precise day to day measurement of circulating antibody was carried out. However, such estimations, even when taking into account the half-life of antibody molecules (1-3) cannot approach the accuracy and reliability of direct measurements. Tracer studies employing labelled amino acids offer a means of determining rates of antibody synthesis directly, and recently two such studies have been reported (4, 5). These two reports, which dealt with the early phases of antibody synthesis in the secondary response, were in disagreement concerning the amount of antibody formed during the first 3 days after injection of antigen.In the present investigation, we have obtained data concerning rates of antibody synthesis throughout the first, second, and hyperimmune responses with special emphasis on the rate of decline of antibody production. Bovine gamma globulin was chosen as the antigen because there are available extensive, albeit conflicting, observations of its fate in rabbits. It was hoped that knowledge of the rates of antibody synthesis might throw light on this area of disagreement. EXPEI~ I]Vf~NTA L P R O C E D U R EUse was made of the fact that amino acids are incorporated into proteins or catabolized and/or excreted within a few hours after their injection into animals. In rabbits virtually all of the initial incorporation of injected S35-1abelled amino acids into proteins occurs within 12 hours (6). We have observed that within 7 hours after injection more than 90 per cent of the original free S35-1abelled amino acid is lost from the serum.

Impairment of the Antigenicity of a Protein Antigen Following Its Injection Into Rabbits

“…The relatively short survival of injected antigen, in its intact form, as indicated by the present findings and in the reports of some of the authors mentioned above (22)(23)(24)(25)(26)(27), stands at variance with observations obtained in previous work from this laboratory (2)(3)(4). In that work, as already stressed, bovine ~'-globulin, injected into donor rabbits as an antigen, seemed to persist in their livers for 6 weeks or more, as judged by the fact that transfers of the donors' liver tissue after these periods rendered recipient mice anaphylactically sensitive to the antigen given to the donors (4).…”

“…It is to be stressed that only a very short persistence of intact antigen has been reported by Coons and his coworkers (22)(23)(24), using tluorescein-conjugated antibody to detect histologically the possible sites of antigen retention. Dixon and his collaborators (25)(26)(27), working with the I TM label, find no evidence for antigen retention in the blood after antibody formation becomes well established, nor do they find evidence for its long retention in the tissues. They point out (25) that the decline of antibody formation 7 or 8 days after an in~ection of antigen indicates the loss of the effective antigenic stimulus for serologically demonstrable antibody formation.…”

“…Dixon and his collaborators (25)(26)(27), working with the I TM label, find no evidence for antigen retention in the blood after antibody formation becomes well established, nor do they find evidence for its long retention in the tissues. They point out (25) that the decline of antibody formation 7 or 8 days after an in~ection of antigen indicates the loss of the effective antigenic stimulus for serologically demonstrable antibody formation.…”

Gamma Globulin and Antibody Formation in Vitro

“…A more rapid and elevated production of antibody upon secondary exposure to a protein antigen, given 1 month or more after a primary injection has been repeatedly demonstrated (12)(13)(14)(15)(16). The increase in the rate of antibody formation i~ dtro on day 2 after the booster injection, observed by Dutton eta/.…”