Studies on M and G antibody response of mice to bovine serum albumin. II. Induction of tolerance.

Abstract

Tolerogenic effect of soluble deaggregated bovine serum albumin (sBSA) on the γM and γG antibody responses was studied. Normal and tolerogen-treated animals were immunized with the intravenous injection of alum-precipitated BSA (net 0.1 mg) and a bacterial endotoxin (0.01 mg), since this immunizing procedure was the most adequate to elicit the strong responses of both types of antibodies. Both γM and γG responses were decreased evenly by a single injection of small dose (0.01 or 0.1 mg) of sBSA. Larger doses (1 mg or 5 mg) caused the marked suppression of γM response, but the γG response was reduced only slightly. The tolerant state was facilitated by weekly injections of 0.1 mg of sBSA, both γM and γG responses being abrogated profoundly by more than three injections. The induction of such a complete tolerance was not ascribed solely to either the total dose or the period of time between the first tolerogen injection and the challenge immunization, but to the retention of antigen more than a certain threshold amount in the body for some duration.