Effects of BCG and C. parvum treatment on human melanoma xenografts.

CBA mice rendered immunodeficient by thymectomy, potentially lethal gamma-irradiation and reconstitution with bone marrow cells were used to grow a wide variety of human tumours as subcutaneous implants. Samples of human melanoma obtained at surgery were successfully passaged by transplantation and produced rapidly growing tumours, some of which metastasized to lung, lymph nodes and the para-aortic node; this system was used as a model for the study of immunotherapy of melanoma. Preliminary results show that intratumour injections of C. parvum retard or inhibit the growth of melanoma transplants and, therefore, do not require the involvement of T lymphocytes, whilst BCG has no effect on growth rate.