Growth and Metastasis of Fresh Human-melanoma Tissue in Mice with Severe Combined Immunodeficiency

Cryopreserved cell suspensions of freshly excised melanoma metas-tases from nine patients were injected s.c. into C.B-17 severe combined immunodeficiency (SOD) mice. All 9 tumors grew as s.c. masses and six of nine were successfully transplanted into other SOD mice. Transplant inocula as low as 5 × 105 cells resulted in 100% tumor incidence. Moreover, seven of nine tumors metastasized, five from the original s.c. implants and two from transplanted s.c. tumors. Metastases were detected mainly in the lungs but also were found in abdominal viscera (liver, spleen, and pancreas) and thoracic lymph nodes. Flow cytometric analysis showed that expression of a panel of melanoma antigens, melanoma-associated proteoglycan, ganglioside GDj, and ganglioside GD2, was maintained with SOD passage. The original tumor inocula contained a variable percentage of tumor-associated lymphocytes (1-76%). Flow cytometry analysis indicated that these were mainly CD3+ T-cells. However, there was no correlation between the percentage of tumor-associated lymphocytes and the time required for development of a palpable tumor after s.c. injection or the ability to metastasize. These results demonstrate the growth and spontaneous metastasis of fresh human melanoma in SOD mice and suggest that this model could be important for therapeutic and basic biological studies.