Characterization of human malignant melanoma cell lines; V. Heterotransplantation in the hamster cheek pouch.

Seven continuous cell lines of human malignant melanoma were studied in terms of their in vivo growth potential in the cheeck pouch of the cortisonized golden hamster. Progressive tumor growth was noted only among the melanoma lines which were grossly pigmented (10/32 transplants). None of the three amelanotic tumor lines showed progressive growth. The growing tumors could be identified as melanoma on morphological grounds and by histochemical demonstration of melanin granules. Histology of the tumor lesions revealed evidence of a host reaction to the tumor transplants. This was confirmed by demonstration of circulating antibodies directed against the implanted human cells. Correlations between in vivo heterotransplantability and in vitro saturation density of human melanoma cells were not found in the present study.