Development of a murine model of lymph node metastases suitable for immunotoxicity studies.

INTRODUCTION: Immunosuppressive drugs are associated with an increased risk of infections and in some cases neoplasia, particularly non-melanoma skin cancers. This paper describes the development of a model to test the effects of immunosuppressive drugs on local invasion and metastases of a squamous cell carcinoma in syngeneic, immunocompetent mice. METHODS: SCC VII cells were labeled with 655 quantum dots (QDs), injected intramuscularly into C3H HEN mice and traffic and progressive growth in the draining popliteal lymph node were evaluated. RESULTS: SCC VII cells express RAE-1, an NKG2D ligand, and were sensitive to natural killer (NK) cells in vitro. QDs were stable in SCC VII cells and showed no evidence of toxicity to the cells. In vivo, confocal microscopy showed that QD-labeled SCC VII cells could migrate to the draining node and microfluorimetry showed progressive traffic of QDs to the node. There was no evidence of systemic toxicity of QDs. Primary immunosuppression in SCID and SCID-beige mice and treatment of normal mice with immunosuppressive agents (anti-asialoGM1 and cyclophosphamide) can enhance traffic of QDs and/or metastases to the draining lymph node. In contrast, cyclosporine had no effect on traffic or metastases. CONCLUSION: This model of local invasion and metastases may be useful in immunotoxicology for identifying and characterizing the hazard posed by selective immunosuppressive drugs.