Indium-111 labeled leukocytes in evaluation of active specific immunotherapy responses.

Active immunization of patients utilizing viral oncolysates (VO) has been studied in clinical trials. VO are extracts of cultured tumor cells that have been infected with certain types of viruses, particularly surface budding varieties. The objectives of the current studies were to examine the trafficking patterns of Indium (In)-111-labeled leukocytes or lymphocytes in two groups of patients with gynecologic malignancies to determine whether these cells migrate to sites of active immunization after VO. Eight patients with ovarian cancer received VO intraperitoneally followed by In-111-labeled leukocytes or lymphocytes (500 µCi) intravenously. In a separate trial, three patients with cervical cancer received In-111-labeled lymphocytes after they had been treated with VO administered by the intralymphatic route. Gamma camera imaging was performed to evaluate the distribution patterns of the labeled cells at several time intervals after injection. Results indicate that metastatic tumor sites exposed to VO therapy show significant uptake of In-111 cells. These sites of malignancies were confirmed by computerized tomography and ultrasound scans. In patients with ovarian cancer no uptake of the radiolabeled cells was observed in metastatic tumors of the liver and lymph nodes. In patients with cervical cancer, lymph node metastases exposed to intralymphatic VO therapy were visualized very well. Other known tumor sites not exposed to VO therapy showed no uptake of radioactivity. These findings confirm that VO induces immune responses. This diagnostic nuclear medicine technique may prove to be a useful method for following-up responses to immunotherapy.