The effect of surgical removal of a rat sarcoma on lymphocyte cytotoxicity

The effect of surgical removal of tumors on cytotoxicity reactions was studied in Lewis-Wister inbred rats bearing a transplantable methylcholanthrene-induced sarcoma (MCI). Lymphocyte cytotoxicity and the effect of the serum in blocking (decreasing) or potentiating (increasing) lymphocyte cytotoxicity were studied using MCI tissue culture cells, prelabeled with 3H-proline, as target cells. After surgical removal of the tumors, tumor nodules were again palpable in all rats by the seventh day after surgery and regrew at an accelerated rate. In control rats bearing the MCI sarcoma, serum blocking activity appeared between the 8th and 13th days and completely inhibited lymphocyte cytotoxicity until death of the animals. Surgical removal of the tumors resulted in a decrease in lymphocyte cytotoxicity and complete absence of serum blocking activity for at least 7 days. By the 13th day, when tumors were again growing rapidly, lymphocyte cytotoxicity had increased markedly, and blocking activity again appeared in the serum.