Distinct tumour specificity and IL-7 requirements of CD56 - and CD56 + subsets of human γδ T cells

Abstract

γδ T cells are believed to recognize tissue injury caused by infections, tumours, as well as chemical and physical agents. The present study was carried out to study the feasibility of the ex vivo expansion of γδ T cells from healthy individuals, and to determine their functional capacity against tumours. We selectively expanded the peripheral γδ T cells of five donors against a myeloma cell line, XG-7. Under optimal conditions, the resulting bulk cultures comprised about 82% of the γδ T cells, more than 90% of which showed the T-cell receptor (TCR)-Vγ9δ2 rearrangement. These γδ T-cell cultures exhibited TCR-γδ dependent cytotoxicity against different tumour cell lines including Molt-4, BJAB, Epstein-Barr virus (EBV) transformed lymphoid cell lines (LCL), and the nasopharyngeal carcinoma (NPC) cell lines, CNE2 and 915, in addition to the stimulator XG-7. By competitive cytotoxicity assays, the γδ T cells demonstrated recognition of at least three distinct target specificities expressed by Molt-4, CNE2 and LCL. respectively, which were related to that expressed by the stimulator XG-7 cells. The recognition of the specificity expressed by XG-7 and Molt-4 was further shown to require the participation of heat shock protein (HSP). The specificity expressed by CNE2 and 915 was preferentially recognized by the CD56- subset of γδ T cells, which could be sustained in the presence of interleukin (IL)-7. These results suggested that γδ T-cell immunity against tumour cell lines may be acquired in response to other types of tissue injury and, hence, implicates a role for their use in the prevention and treatment of tumours.