Pir-B inhibits the DC function and disturbs the Th17/Treg balance in lung cancer murine model

Paired immunoglobulin-like receptor B (Pir-B) was an inhibitory receptor expressed on the surfaces of dendritic cells (DCs). Pir-B inhibit T helper (Th) 1 response and induce Th2 cell differentiation, leading to the imbalance of Th1/Th2 cells. However, the role and potential mechanism of Pir-B on the balance of Th17/regulatory T cells (Tregs) is still largely unknown in lung cancer murine model. In the present study, the DC function and Th17/Treg balance were destroyed during the progression of lung cancer and this was accompanied by an increased expression of Pir-B. After transfection with Pir-B siRNA or administration of IL-6 in vitro, the decreased response of Th17 cells were restored, whereas the augmented differentiation of Tregs was diminished. Further, the transfer of Pir-B silenced DCs or the injection of IL-6 in vivo increased Th17 response and decreased Treg differentiation. Our study has demonstrated that Pir-B inhibits the DC function and disturbs the Th17/Treg balance via IL-6 pathway during the progression of lung cancer, contributing to inhibited antitumor immunity.