C. G. BULL 737 



sensitized to the toxic efifects of the serum; third, the uterine muscle of normal guinea 

 pigs fails to contract when exposed to heterophile serum; fourth, heterophile serum 

 injected into the skin of guinea pigs causes a characteristic local necrosis; fifth, the 

 toxic property of a pure heterophile immune serum is directly proportional to its hemo- 

 lytic power, and the two properties cannot be separated by fractionation with am- 

 monium sulphate, the globulin fraction containing both properties. 



In regard to the antibody content of heterophile-immune sera one can state, then, 

 that they apparently contain specific hemolysin, precipitin, hemagglutinin, and com- 

 plement-fLxing antibodies and a specific substance toxic for animals whose tissues con- 

 tain heterophile antigen. However, one may ask here, as with ordinary antibodies, 

 whether we have five distinct substances or whether one substance gives the five dif- 

 ferent effects under different conditions. 



PRACTICAL ASPECTS 



Besides offering an explanation of many instances of serum intoxication, knowl- 

 edge of the occurrence of heterophile antigen in the tissues of certain animals and 

 the occurrence of the antibody in the body fluids of other species is of practical 

 importance. For example, the tissues of guinea pigs contain the antigen and, as will 

 be recalled, the antigen appears in preparations of lecithin from such tissues. Human 

 serum may contain heterophile antibody. Hence, it would be possible to have falsely 

 positive Wassermann reactions if the antigen were prepared from the heart muscle 

 of guinea pigs, or from any tissue containing heterophile antigen. 



The possibility of making use of the heterophile reaction in the identification of 

 meats has also been pointed out. One could determine, for example, if sausage con- 

 tained horse, dog, or cat flesh, even after it had been cooked, by making a test for the 

 presence of heterophile antigen. However, if sheep or goat blood were present, the 

 test would not be applicable, for these also contain the antigen. 



SUMMARY 



In 191 1 Forssman discovered the substance now known as "heterophile anti- 

 gen." This substance occurs in the tissues of a number of mammals, birds, fishes, and 

 bacteria, namely, sheep (blood cells and sperm), goat (blood cefls), horse, dog, cat, 

 camel; chickens; lobster, carp, pike; Shiga dysentery bacilli, certain paratyphoid or- 

 ganisms, and a certain strain of Bacterium lepiscpticum. 



Chemically, heterophile antigen seems to be a lipoid-protein complex. It is very 

 resistant to heat. The complex can be disrupted by treatment with alcohol and other 

 lipoid solvents. 



When injected into rabbits, or other animals whose tissues do not contain the 

 antigen, heterophi'e antigen stimulates the production of antibodies, namely, hemol- 

 ysins for sheep and goat corpuscles; precipitins, specific for the antigen; hemagglu- 

 tinins, especially for aged sheep corpuscles; complement-fixing antibody, also specific 

 for the antigen, and a substance toxic for guinea pigs or other animals whose tissues 

 contain the antigen. 



For the stimulation of antibody production the whole lipoid-protein complex is 



