Tolerance to alloantigens of the A and B systems in chickens.

Tolerance to alloantigens of the A and B systems in chickens has been induced by multiple injections of RBC and tested by the elimination of 51Cr-labelled RBC of the same specificity. Three doses consisting of at least 108 RBC each in the B system and 107 RBC in the A system were needed to induce tolerance in newly hatched chicks. Futhermore, it was found that large doses, 109 RBC, in both systems induced tolerance in 100% of week-old and 50% of 14-day-old chickens. With doses of 109 RBC, tolerance to the B antigen disappeared at 8 days in the absence of RBC, whereas in the case of the A antigen it disappeared after more than 50 days, and with the 107 cell doses after 35 days. The elimination of A-incompatible RBC was proportional to the amount of anti-A antibodies present in the recipient's circulation, whereas a minimal amount of antibodies was capable of considerably accelerating the elimination of B-incompatible RBC.