Heteroimmunogenicity of human salivary blood group A substance in rabbits.

Rabbits were selected on the basis of distinctly higher titers of preexisting heteroagglutinins in their normal sera for human group A1 and A2 erythrocytes than for group B and especially group O. They were injected intravenously with increasing volumes of either of two pools of human group A1 secretor saliva. Comparative titrations between the reimmunization and the 7--14-day postimmune sera clearly demonstrated that all the rabbits responded with increases in the titers of the agglutinins directed against human group A1 and group A2 red blood cells that averaged approximately 250-fold; whereas, the titers of those active against the group B cells increased but 9.2 times and of those reacting with the group O cells only by an average of 2.8 times.