REGIONAL LOW-DOSE INTERLEUKIN-2 IMMUNOTHERAPY OF LYMPH-NODE MICROMETASTASIS IN A GUINEA-PIG TUMOR-MODEL

Strain 2 guinea pigs bearing the transplanted intradermally growing li ne 10 tumor underwent surgical excision of the primary lesion at a tim e when the tumor had already metastasized to the first draining lymph node. Postoperative perilymphatic immunotherapy with 500 or 5,000 IU o f interleukin-2 (IL-2) for 12 consecutive days failed to cure the anim als of residual lymphatic micrometastasis. Similarly, intratumoral IL- 2 treatment of nonoperated guinea pigs did not alter the natural cours e of the disease. However, histological serial examination of the tumo r-draining lymph nodes at the end of immunotherapy revealed significan tly less tumor occupation in all IL-2-treated animals as compared to c ontrol animals.