48 



D. A. L. DAVIES 



Table I 

 Production of H-2 antisera 



Chemical methods 



The chemical methods used have been standard procedures: 

 nitrogen by Kjeldalil; phosphorus by Fiske and Subbarow; total 

 protein by ninhydrin after acid hydrolysis ; total carbohydrate by 

 orcinol; nucleic acid by absorption at 260 m(x; hexosamine as 

 described by Rondle and Morgan (1955) and sialic acid by the 

 method of Warren (1959). 



Purification of H-2 antigen 



Preliminary experiments 



When tumour cells were tested for their ability to absorb 

 haemagglutinating antibody from H-2 antisera, it became clear 

 that they carried H-2 specificity on their surfaces. For these 

 experiments blood cells were removed from the tumour-cell 

 suspensions by sedimenting through a sucrose gradient. The 

 presence of H-2 specificity on the tumour cell surface could be 

 shown more clearly by mixed agglutination (Coombs, Bedford 

 and Rouillard, 1956) when dextran and NHS were used in the 

 system and non-specific cells (LAN) as control (Boyle, 

 unpublished). The examination of ascitic fluids from which the 



