Heterophile antibodies and antigens in neoplastic diseases

I L E antigens are antigenic materials common to two or more species of organisms that are phylogenetically unrelated.For example, an apparently identical antigen has been demonstrated in pneuniococci and in sheep erythrocytes.One of these heterophile antigens, occurring in the kidney and other organs of guinea pigs and also in sheep erythrocytes, was characterized by Forssman and hence is known by his name.Antibodies against these antigens can be produced by inoculation into suitable animals.For example, rabbits inoculated with guinea-pig kidney will produce antibodies against guinea-pig kidney and against sheep erythrocytes.Man too will produce heterophile antibodies in response to injected antigen.In serum sickness, for example, a rise in sheep-erythrocyte-agglutinating (heterophile) antibodies results from the injection of the heterophile antigen of horse serum.Heterophile antibodies in high titer also occur in man without the stimulus of known antigens in infectious mononucleosis and sometimes in viral hepatitis.T h e niajor clinical importance of the hetcrophile-antibody reaction is in the diagnosis of infectious mononucleosis and in the differential diagnosis of this disease from acute leukemia.Usually this differential diagnosis is simple on clinical grounds, but the occasional case of acute leukemia in which a spontaneous rcmission occurs may make the physician consider the happier diagnosis.About 10 per cent of iniectious-mononucleosis patients fail to exhibit a diagnostic titer of heterophile antibodies, thus making a "negative" sheep-cellagglutination test of no value in this differcntial diagnosis, but it has been almost universally accepted that a high heterophile titer safely excludes the diagnosis of acute leukeniia.Two patients with acute leukemia were ~~