DISCUSSION l8l 



appearance of these lymphoid tissues in relation to the tumours, but 

 only tested for the existence of viable tumour cells by making cell sus- 

 pensions of such organs and retransplanting. 



Nakic: Dr. Loutit, are the animals suffering from the secondary 

 disease immunologically incapacitated ? 



Loutit: Not entirely. But this is a very complex subject. 



Nakic: We have had quite a different experience, although I am 

 talking of a different experimental model — parabiosis between adult 

 rats. We have found that animals tolerant of the cross-graft and dying 

 of graft-versus-host reaction, with approximately the same histological 

 picture you describe, can reject the graft from the third strain, although 

 after some delay. 



Woodruff: Dr. Feldman has shown that you can have tumour cells 

 that have distributed themselves amongst lymph nodes and remain 

 quiescent without developing metastases. We should remind ourselves 

 that this is a fairly familiar phenomenon with spontaneous human 

 tumours, and it is not confined to lymph nodes. This is illustrated by 

 the following case. A patient who had had a melanoma removed three 

 years previously from a leg, had a carcinoma of the breast treated in the 

 orthodox way by a combination of surgery and radiotherapy, and 

 within three weeks hundreds of thousands of melanomata appeared 

 simultaneously in the field of irradiation. I think the only possible con- 

 clusion is that these cells were present for three years in the subcut- 

 aneous tissue but remained quiescent until the equihbrium between 

 tumour and host was disturbed by the mechanical trauma of the 

 operation, or the irradiation, or both. 



Another point, following on what Dr. Loutit was saying, is that 

 since irradiation (or administration of cytotoxic drugs) produces wide- 

 spread damage to normal lymphoid tissue, it is desirable in treating 

 patients with these agents to try to undo some of this incidental harm 

 you have done, by taking out the patient's spleen before starting treat- 

 ment and putting it back intravenously in the form of a cell suspension 

 afterwards. We have reported a number of cases in which we have done 

 this (Woodruff, M. F. A. and Nolan, B. [1961]. Lancet, 2, 689). 



Feldman: I fully agree with you. I think that the very fact that some 

 type of resistance can be shown within the lymph nodes towards pre- 

 existing tumour emboH tends to support your interpretation. The 



