IMMUNITY IN TUMOR TRANSPLANTATION 429 



against cancer antigens in the serum of cancer patients, mixed alcohol extracts 

 from a human carcinoma with the blood serum of patients suspected of cancer 

 and observed a specific complement fixation. A positive reaction was obtained 

 irrespective of the organ in which the carcinoma had arisen. However, other 

 investigators consider this test as non-specific, or at best, as successful in 

 only a small number of instances. Lehmann-Facius, in order to demonstrate 

 the presence of specific immune substances in the serum of cancer patients, 

 used the euglobulin fraction of the serum and the phosphatid fraction of 

 tumor extracts. Also, the diagnostic cancer reactions of Freund and Kaminer, 

 of Willheim and Stern, and of Fuchs, are based on the assumption that in 

 the serum of cancer patients substances are circulating which are specific 

 for all kinds of human cancer, which develop in response to antigens charac- 

 teristic of cancer, and which interact with these antigens in a specific manner. 

 The substances present in the cancer sera may be either proteolytic or lipolytic. 

 Moreover, not only human cancers, but also animal cancers, may contain 

 these antigens. But there is still some difference of opinion as to the degree 

 of specificity attaching to these various tests. 



We have already referred to the experiments of Lumsden, who believes 

 that besides preformed natural and experimentally produced immune sub- 

 stances which are species-specific, there exist in the serum constituents which 

 act in a specific manner on various kinds of cancer cells growing in vitro, 

 although they are able to injure, also, reticuloendothelial cells growing out 

 from pieces of spleen in tissue culture. As stated, it is not certain at present 

 whether these reactions are due to the species differentials present in cancer 

 and in spleen tissue, or whether they are due to "antimalignancy" antigens, 

 calling forth the production of the corresponding antibodies. On the whole, 

 the evidence seems to point to the conclusion that the reactions which Lumsden 

 observed were caused by species differentials, therefore, by organismal differ- 

 entials, and not by a special kind of antigen, designated by this investigator 

 as "antimalignancy" antigens. More recently, Mann and Welker produced 

 in rabbits, injected with preparations from various types of human cancer, 

 antisera which contained precipitins for the proteins present in autolysed 

 carcinoma, but not as a rule for proteins from normal human tissues ; these 

 immune substances reacted also with the blood serum from cancer patients, 

 and most strongly with the serum of patients that were bearers of the same 

 kind of carcinoma as the one from which the antigens that were used in the 

 preparation of the precipitins had been obtained. This suggests that the specific 

 carcinomatous proteins are present also in the blood of cancer patients. Such 

 serum is species-specific; it reacts only with human sera, not with those of 

 various animal species. These precipitins were therefore, specific for protein 

 from carcinoma and at the same time they were species-specific. 



There is, furthermore, noticeable in some of the diagnostic tests for cancer 

 mentioned above, a similarity between the reactions of cancer sera and of 

 embryonal or pregnancy sera; embryonal cells may be affected by these sera 

 in a similar manner to cancer cells, and in embryonal tissue, antigens similar 

 to cancer antigens may be present. Moreover, Hirszfeld and Dmochowski 



