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 line 10 tumor underwent surgical excision of the primary lesion at a time when the tumor had already metastasized to the first draining lymph node. Postoperative perilymphatic immunotherapy with 500 or 5,000 IU of interleukin-2 (IL-2) for 12 consecutive days failed to cure the animals of residual lymphatic micrometastasis. Similarly, intratumoral IL-2 treatment of nonoperated guinea pigs did not alter the natural course of the disease. However, histological serial examination of the tumor-draining lymph nodes at the end of immunotherapy revealed significantly less tumor occupation in all IL-2-treated animals as compared to control animals.