l64 MICHAEL FELDMAN AND DAVID YAFFE 



used both a tumour of recent origin, the sarcoma Cio, produced 

 in C3H mice by 3 : 4-benzpyrene, and a long-transplanted tumour 

 of C3H origin, the sarcoma MCiM. It is seen (Table I) that infant 

 spleen cells from 8-day-old donors, following colonization of 

 lethally irradiated isologous hosts, can induce transplantation 

 immunity. The cells (spleen or foetal Hver) were inoculated 24 

 hours following X-irradiation, and the tumours were grafted 

 subcutaneously immediately afterwards. The rejection of homo- 

 grafts of both tumours by the genetically foreign spleen chimeras, 

 and their progressive growth in the foetal liver chimeras, indicate 

 that the immune response has been produced by the donor-type 

 cells. The rejection of the MCiM homografts by the C57BL 

 chimera shows, in fact, that the immune response produced by 

 the donor cells is intense, since this tumour possesses the capacity, 

 under certain normal conditions, to resist the homograft reaction 

 (Feldman and Sachs, 1957). 



It should, however, be pointed out that different results were 

 obtained when isologous bone marrow chimeras were tested 

 for their immunological reactivity (Barnes et ah, 1957; Koller, 

 Doak and Davies, 1961). Isologous BALB/c bone marrow chim- 

 eras behaved similarly to BALB/c foetal cell chimeras when 

 challenged with a homograft of the C3H-originating sarcoma 

 BP8: in both groups a progressive growth of the homograft was 

 obtained when the tumour was challenged on days o to 25 

 following bone marrow transplantation. Similar results were 

 obtained when skin was used as a test homograft (Koller, Doak 

 and Davies, 1961). It thus appears that infant spleen cells, follow- 

 ing repopulation, confer on the host a high degree of immuno- 

 logical reactivity, whereas the immunological reactivation of 

 bone marrow chimeras is delayed. 



Tumour metastasis 



Malignancy in human sarcomas is generally associated with 

 the progression of tumour metastasis. On the other hand, most 



