Although IL-27 was extensively investigated in conventional T cells [[2, 5]], its role on TCRγδ+ T lymphocytes remains unexplored. The latter cells, which are mainly Vγ9Vδ2+ in

human peripheral blood and poorly represented in physiological conditions (1–5% of circulating lymphocytes), may be strongly activated and expanded by nonpeptide phosphoantigens expressed by transformed or pathogen-infected cells [[6-9]]. In this context, we recently demonstrated that IL-27 acts as ACP-196 purchase antitumor agent by targeting directly human hematological tumors including multiple myeloma, B-acute lymphoblastic leukemia, and B-cell lymphoma of germinal center origin [[10, 23, 24]]. However, it has been reported that TCRγδ+ T lymphocytes kill a vast repertoire of tumor cell lines and primary samples in vitro including leukemia, lymphoma, melanoma, neuroblastoma,

and different MI-503 types of carcinoma, thus raising great interest in targeting TCRγδ+ T cells for cancer immunotherapy. In addition, TCRγδ+ T lymphocytes interplay with conventional T cells, B cells, NK cells and dendritic cells, neutrophils, and macrophages, thus representing a T-cell population with a critical role in both innate and adaptive immunity [[6, 11-22]]. With this in mind, we investigated the functional role of IL-27 on human TCRγδ+ T lymphocytes, either freshly isolated from peripheral blood of normal subjects or expanded in vitro upon PBMC stimulation with zoledronic acid, and asked whether IL-27 could modulate the functional properties of TCRγδ+ T cells. Resting and activated Vγ9Vδ2+ T cells expressed WSX-1 (mean relative of fluorescence intensity (MRFI) ± SD: resting 1.76 ± 0.005, activated 3.97 ± 0.56, diglyceride Fig. 1A and B) and gp130 (MRFI ± SD: resting 3.11 ± 0.15, activated 2.63 ± 0.02, Fig. 1A and B) chains, thus indicating that both cell populations may be responsive to IL-27.

The complete IL-27R was functional in these cells, as witnessed by the ability of IL-27 to significantly induce STAT1 (MRFI ± SD: medium 1.87 ± 0.02, IL-27 13.99 ± 0.24, p < 0.0001), STAT3 (MRFI ± SD: medium 1.56 ± 0.32, IL-27 2.97 ± 0.11, p = 0.006), but not STAT5 (MRFI ± SD: medium 1.25 ± 0.01, IL-27 1.3 ± 0.02) (Fig. 1C and D) phosphorylation. Thus, TCRγδ+ T cells show a similar behavior to classical T lymphocytes in terms of IL-27R expression and IL-27-driven signaling pathway [[1, 2]]. Finally, the significant differences in WSX-1 (p = 0.03) and gp130 (p = 0.05) expression between resting and activated Vγ9Vδ2+ T cells may be conceivably related to the different experimental conditions used, that is, in vitro expansion by zoledronic acid versus direct isolation of TCRγδ+ T cells from peripheral blood (PB). However, such differences did not significantly impact on STAT-1, STAT-3, or STAT-5 activation (not shown) or other functional responses to IL-27 (i.e. cytotoxicity, see below).