Heterophile antigen
Heterophile antigens: certain antigens of similar nature, if not identical, present in different tissues in different biological species, classes or kingdoms. Composition: chemically these are lipoprotein-polysaccharide complexes, possibly there are identical chemical groupings in the structure of mucopolysaccharids and lipids. Example: Forssman antigen, cross reacting microbial antigen so antibodies to these antigens produced by one species cross react with antigens of other species.