Characteristics of human tumour xenografts transplanted under the renal capsule of immunocompetent mice.

Human tumour lines established in athymic nude mice were grafted under the renal capsule of immunocompetent mice. Grafts from 27 human tumour lines comprising 9 malignant melanomas, 10 sarcomas, 2 colon carcinomas, 4 lung carcinomas and 2 mammary carcinomas, grew well under the renal capsule of the immunocompetent mice and retained morphological and functional characteristics of the parent tumours, as judged by light and electron microscopy and immunohistochemical examinations. Numerous mitoses were detected. Granulation tissue and necrosis were not predominant features. After Day 4, the grafts became infiltrated from the periphery by mouse inflammatory cells. The infiltration could be prevented by pretreatment of the animals with cyclophosphamide. Anti-human antibodies were detected after Day 3. Single cell suspensions from the subrenal grafts were able to form colonies in soft agar. and upon reimplantation in nude mice, subcutaneous tumours were formed showing that the grafted tumour tissue had also retained its malignant character. Altogether the results support the view that human tumour xenografts grow well under the renal capsule of immunocompetent mice and that the grafts retain important characteristics of the original tumour.