AN ISOANTIGENIC LIPOPROTEIN FROM 

 SARCOMA I* 



A. A. Kandutsch and Jack H. Stimpfling 



Roscoe B. Jackson Memorial Laboratory, Bar Harbor, Maine 



The earliest investigations into the nature of the transplantation 

 isoantigens responsible for the phenomenon of immunological 

 enhancement were carried out by Snell (1952) and by Day and 

 co-workers (1954). We have continued to rely chiefly upon the 

 enhancement test as a measure of tissue isoantigens and, in more 

 recent stages of this work, use has been made of a haemagglutina- 

 tion inhibition assay. The enhancement phenomenon is dependent 

 upon the production in host mice of circulating antibodies specific 

 for the isoantigens present in a tumour homograft (review by 

 Snell, 1957). The enhancement assay is, therefore, a measure of 

 complete antigens. In contrast the haemagglutination inhibition 

 assay may be expected to show a positive test with haptenic or 

 non-antigenic fragments as well as with complete antigens. The 

 inhibition test also provides a means for assaying the activity of 

 antigen specificities which are shared by the particular donor and 

 recipient strains (A and B10.D2 — an H-i"^ subline of C 5 7BL/ 10) 

 used in the enhancement test, while the enhancement test measures 

 only the activity of antigens present in the A strain but absent 

 from B10.D2. The enhancement assay was carried out as 

 described previously (Kandutsch and Reinert-Wenck, 1957). 

 The haemagglutination-inhibiting properties of different prepara- 

 tions were determined by means of the polyvinylpyrrolidone 



* Supported by a grant from the American Cancer Society (E-26) and by 

 Research Grant C-1329 from the National Cancer Institute, United States Public 

 Health Service. 



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