Tolerance induction in TxXBT and TxXB mice.

Adult normal mice and those mice which had been thymectomized, X-irradiated, and reconstituted either with bone marrow cells and thymus cells (TxXBT) or with bone marrow cells along (TxXB), were given varying amounts (0.1-5 mg) of deaggregated soluble bovine serum albumin (sBSA). They were challenged 10 days later with an immunogenic form of BSA. TxXB mice were supplemented with normal thymus cells 3 days before the challenge. With any dose of sBSA, TxXBT and normal mice were made tolerant. Only 5 mg of sBSA, the highest dose in these experiments, was effective in inducing the tolerance in TxXB mice. The simultaneous administration of 5 mg of sBSA and 0.1 mg of alumprecipitated BSA plus 0.01 mg of endotoxin resulted in the priming in TxXBT mice but induced tolerance in TxXB mice. These results indicate that: (a) B-cell tolerance could be induced independently of the influence of T cells; (b) the tolerogen susceptibility of B cells may be lower than that of T cells; (c) such a weakly immunogenic agent as the mixture of tolerogen and immunogen could either activate the antibody response in the presence of T cells or induce B-cell tolerance in the absence of T cells.