The production of anti-a1 agglutinins in A-like rabbits injected with human group A1 erythrocytes.

A-like and non-A-like rabbits were injected with human group A1 erythrocytes. The rabbit sera were examined serologically for their hemagglutination patterns with human red cells of groups A1 and A2 before and after sequential adsorption with human group O, B and A2 erythrocytes. The A-like rabbits produced specific anti-A1 heteroagglutinins that resisted further adsorptions with group A2 cells. The tissues of A-like rabbits obviously do not contain antigenic configurations equivalent to those on human group A1 erythrocytes. Cross-reacting antibodies were also formed, by the non-A-like rabbits especially, as evidenced by the increased titer of agglutinins reactive with human group B red cells.