Relationship between anti-A and anti-Forssman.

Antibodies that detect a spectrum of A antigenic specificities have been demonstrated in human anti-A sera. Some sera contain antibodies that detect a specificity common to human A red cells and buccal cells, sheep R, r and i red cells, pig A red cells as well as guinea-pig kidney cells. Antibodies reacting with the A determinant on pig A red cells may be absent from some sera. Another antibody detects an antigenic specificity present on human A red cells and buccal cells, pig A and sheep R red cells, and perhaps also on guinea-pig kidney, but absent from sheep r or i red cells. Other antibodies detect an A antigen present only on human A red cells.