Malignant cell arrest in thymus and spleen of mice bearing transplanted tumors.

The relationship between the local outgrowth of different subcutaneous transplantable tumors (plasmacytoma MOPC-315, mastocytoma P-815; Lewis lung carcinoma-3LL; fibrosarcoma; lymphomas and mammary adenocarcinoma) and tumor cell spread in different organs was evaluated. The presence of tumor cells in thymus, spleen, lung, and liver was demonstrated by using both in vivo and in vitro methods. Sequestration of tumor cells derived from the transplanted solid tumor was indicated within 3 to 7 days after tumor graft, shortly before or after early palpable outgrowth of the primary tumor was observed. Tumor cells present in thymus and spleen might affect immune responses of tumor-bearing mice.