Application of gamma-delta T cells obtained by ascites filtration for immunotherapy against malignant refractory ascites

Ovarian cancer often presents with carcinomatous ascites effusion. Cell-free and concentrated ascites reinfusion therapy (CART) provides a symptomatic treatment. The ascitic fluid contains a large number of lymphocytes including γδ T cells which are cytotoxic and used as effector cells in cancer immunotherapy. We collected ascites-infiltrating lymphocytes (AILs) from the ascitic fluid that was obtained for CART. We examined four patients with ovarian cancer and two patients with primary peritoneal cancer. Five patients were at stage 3c, and one was at stage 4b. In patients with ascitic ovarian cancer, in which ascites is accumulated, we collected AIL from a filter and were able to culture γδ T cells. The number of cultured Vδ2 T cells were 3.2 (range, 0.7–63) × 10/L. We cultured AILs obtained from CART with pyrophosphomonoester or zoledronic acid (Zol) as an antigen, interleukin (IL2), and with or without IL18. In case of culture in pyrophosphomonoester, IL2, and IL18, the proportion of Vδ2 T cells / CD3 positive cells was 71%, and the proliferation rate (cell number after culture/those pre-culture) of Vδ2 T cells was 83. Cells cultured in Zol, IL2, and IL18 in AILs exhibited isopentenyl pyrophosphate (IPP)-dependent cytotoxicity, and the median level of it was 5.3%. γδ T cells from AILs obtained from CART have a cytotoxic activity. However, the cytotoxic activity was low, which needs improvement. In future, we may use it as a source for adoptive immunotherapy, if we can improve the proliferation rate and cytotoxic activity.