Prevention of tolerance induction by simultaneous administration of anti-Lyb3 antiserum with tolerogen.

Lyb3 serves as a triggering receptor on a mature subset of B lymphocytes. To further investigate the nature of the activating signal received by this receptor, we examined its involvement in hapten-specific B cell tolerance induced in vivo with isologous IgG. We obtained the following results: injection of anti-Lyb3 serum simultaneously with low doses of tolerogen prevented tolerance induction in B cells responsive to TD and TI type-1 antigens but failed to influence B cells responding to a TI type-2 antigen. Furthermore, administration of anti-Lyb3 serum did not change the tolerogenic signal to an immunogenic one, allowing B cell maturation into plaque-forming cells. However, it did make the B cell responsive to a subsequent challenge with antigen. This effect is transient, and dependent on the dose of tolerogen. These results are discussed in terms of our knowledge of the mechanism of B cell tolerance.