The specificity of anti-A agglutinins from immunized rabbits and plant lectins.

A+ and A- rabbits were immunized with human A red cells, saliva of A+ or A- rabbits or human A.Se. A- rabbits responded well against A.Se saliva and A cells and slightly against A+ saliva, whereas A+ rabbits produced high-titered antibody against A cells which was abolished by absorption with O cells. Agglutination inhibition tests showed that anti-A from A- rabbits immunized with A.Se or A cells was not inhibited with A+ saliva, and anti-A from rabbits immunized with A cells was not absorbed with A.Se saliva. Hydroxylapatite chromatography separated each of A.Se and A+ saliva into three fractions of which the 1st and 3rd fractions of A.Se and only the 3rd of A+ had A activity. The 3rd fraction of A.Se and A+ did not inhibit anti-A from any rabbits immunized but the 1st of A.Se inhibited anti-A from all rabbits except for A+ immunized with A cells. The 1st and 2nd fractions reacted slightly with anti-A from A- immunized with A+ and from A+ immunized with A cells. D. biflorus anti-A distinguished human A from rabbit one but Mushroom anti-A could not. These results suggested qualitative differences between human and rabbit saliva A antigens.