Human CD4⁺iNKT cell adoptive immunotherapy induces anti‐tumour responses against CD1d‐negative EBV‐driven B lymphoma

Abstract

Invariant natural killer T (iNKT) cells are a conserved population of innate T lymphocytes that are uniquely suitable as off‐the‐shelf cellular immunotherapies due to their lack of alloreactivity. Two major subpopulations of human iNKT cells have been delineated, a CD4− subset that has a TH1/cytolytic profile, and a CD4+ subset that appears polyfunctional and can produce both regulatory and immunostimulatory cytokines. Whether these two subsets differ in anti‐tumour effects is not known. Using live cell imaging, we found that CD4− iNKT cells limited growth of CD1d+ Epstein–Barr virus (EBV)‐infected B‐lymphoblastoid spheroids in vitro, whereas CD4+ iNKT cells showed little or no direct anti‐tumour activity. However, the effects of the two subsets were reversed when we tested them as adoptive immunotherapies in vivo using a xenograft model of EBV‐driven human B cell lymphoma. We found that EBV‐infected B cells down‐regulated CD1d in vivo, and administering CD4− iNKT cells had no discernable impact on tumour mass. In contrast, xenotransplanted mice bearing lymphomas showed rapid reduction in tumour mass after administering CD4+ iNKT cells. Immunotherapeutic CD4+ iNKT cells trafficked to both spleen and tumour and were associated with subsequently enhanced responses of xenotransplanted human T cells against EBV. CD4+ iNKT cells also had adjuvant‐like effects on monocyte‐derived DCs and promoted antigen‐dependent responses of human T cells in vitro. These results show that allogeneic CD4+ iNKT cellular immunotherapy leads to marked anti‐tumour activity through indirect pathways that do not require tumour cell CD1d expression and that are associated with enhanced activity of antigen‐specific T cells.