Lethality of human melanoma cells for normal mice immunosuppressed with cyclosporin A

After intraperitoneal inoculation of BRO human melanoma cells, phenotypically immunocompetent mice given cyclosporin A (CyA) developed extensive and lethal tumors. Survivals were not significantly different for normal mice treated with this immunosuppressant compared to nude mice, which lack functional T-lymphocytes. BRO cells could be passaged in CyA-treated mice without alteration of isozymes or other properties tested. This model may have implications for growth and metastasis of human tumors under immunosuppressed conditions and may be useful for studying the mechanism of action of CyA in vivo.