Increase of lymphocyte‐mediated tumor‐cell destruction by certain patient sera

Sera from one patient with an ovarian carcinoma, one with sarcoma, one with a breast carcinoma, and four patients with melanoma were found to “potentiate” (i.e. increase) the cytotoxic effect of blood lymphocytes reactive to the respective type of tumor target cells. This effect was specific. Furthermore, sera from the breast cancer and sarcoma patients and from one of the melanoma patients “armed” (i.e. made cytotoxic) lymphocytes from non‐reactive donors, not having (had) the respective tumor studied. The possible relevance, in vivo, of these findings, and the frequency with which they occur, need further clarification.