46 D. A. L. DAVIES 



Herzenberg, 1961), that DNA and RNA are not components of 

 the antigens (Haskova and Hrubesova, 1958; Castermans, 1961, 

 and others), and that protein, and also probably carbohydrate and 

 hpid are present in the preparations of the T, E and H antigens so 

 far obtained (Kandutsch, 1961). The most advanced preparations 

 would seem to be those of Medawar (T), Kandutsch (E) and 

 Herzenberg (H), but it has not been established that the least 

 entity able to carry activity has yet been obtained in any instance. 



Experimental procedures 

 Animals and tumours 



Mice of strains A, CsH/He, C57BL and BALB/c have been 

 used; each of these was mated at random within its colony for up 

 to three generations from a strictly inbred breeding nucleus. 

 Ascites tumours specific for these strains were Sa-i, BP8, EL4 and 

 CL2 respectively ; these tumours are well known and adequately 

 described in the literature. The Landschiitz subUne of the Ehrhch 

 ascites carcinoma (abbreviated LAN) has been used as a ''non- 

 specific" cell for comparative purposes. 



H-2 antisera have been prepared in mice by three or four weekly 

 subcutaneous injections of appropriate tumour cells or spleen 

 cells. Immune ascitic fluid, induced with LAN injected intra- 

 peritoneally five days before the last immunizing injection, has 

 generally been used as source of antibody since this gives a better 

 yield than mouse serum. To avoid confusion, however, this will 

 be referred to hereinafter as antiserum. 



Rabbit anti-mouse sera were prepared by immunization with 

 ascites tumour cells, or with tumour cell ghosts prepared by 

 treatment with strong salt solution until no more soluble material 

 could be extracted (Haughton and Davies, 1962). A prehminary 

 immunization using Freund's adjuvant was folio v/ed by repeated 

 intravenous injections until an adequate response, determined by 

 agar diffusion, had been achieved. 



