Enhanced Antibody Response in the Offspring of Immunized Rats

This is the authors' abstract. We don't add key points for this paper.

The inbred ACI strain of rats responds very well to immunization with poly Glu52 Lys33 Tyr15, whereas the F344 strain responds quite poorly; at least two genes are involved in the control of the antibody response (1). In the course of breeding the animals for these studies, we observed that the offspring of the F344 strain made considerably more antibody when the mothers were immunized with the antigen aggregated with methylated bovine serum albumin prior to becoming pregnant. It is important to define the factors involved in this effect, since they are presumably environmental and could interfere with the analysis of the genetic control of the antibody response. In the studies reported here, the antibody responses of the offspring from unimmunized mothers and from immunized mothers are compared. Each of the immunized mothers received the antigen aggregated with methylated bovine serum albumin. The aggregate was prepared by mixing 0.75 mg of antigen dissolved in water and 0.75 mg of methylated bovine serum albumin in water. The mixture was emulsified with Freund's complete adjuvant containing additional tubercle bacilli, and it was distributed subcutaneously into the hind footpads and into the back of the neck (1). The second dose of antigen was given intraperitoneally 3 weeks later as an aggregate suspended in water. The rats were bled 10 days thereafter and then mated. Two different doses of antigen were used in testing the antibody response of the offspring, since the immune response of the F344 strain to non-aggregated antigen is dose-dependent (1). At a total antigen dose of 1.5 mg, of which the first half was given in Freund's complete adjuvant and the second half was given in water, the rats just began to respond consistently with small amounts of antibody. In contrast, at a total antigen dose of 20 mg, the first half in Freund's complete adjuvant and the second half in water, all of the rats responded with moderately large amounts of antibody. All of the offspring were tested at 8 weeks of age by immunization with the non-aggregated antigen according to the standard protocol: one-half of the total antigen dose in Freund's complete adjuvant subcutaneously into the hind footpads and into the back of the neck and the other half intraperitoneally in phosphate-buffered saline 3 weeks later. The rats were bled 10 days after the second injection of antigen. Before immunization, the offspring of the mothers immunized with a total of 1.5 mg of antigen were bled in order to determine whether any circulating antibody was present. The concentration of antibody was measured by a micro-method using the bromoacetyl cellulose immunoadsorbent (2).