Objective: To explore the effect of T-cell immunoglobulin and mucin domain containing protein-4（TIM-4） on macrophage (M1/M2) polarization and allograft immune rejection by applying specific monoclonal antibodies to block the TIM-4 molecules on the surface of antigen presenting cells. Methods: Balb/c splenocytes were administered into C57BL/6 mice via intraperitoneal injection to set up the alloimmunization model. The immunized mice were divided into anti-TIM-4 group (n=6) and isotype control group (n=6); mice were injected with isotype control immunoglobulin or anti-TIM-4 monoclonal antibody via intraperitoneal, 300 μg per mouse; on the 5th day, mice were received another injection; on the 10th day, the two group mice were sacrificed for subsequent related experiments. The proportion of M1 and M2 macrophages from spleen and peritoneal cavity were detected by flow cytometry (FCM), and the mRNA expression of miR-21, IL-10, p40, p35 and EBi-3 in splenocytes and peritoneal cavity cells were detected by fluorescence quantitative RT-PCR. Results: Compared with the isotype control group, there was no significant difference in the proportion of M1 and M2 of anti-TIM-4 group in the spleen (P>0.05) and the mRNA expression of miR-21 and p40(P>0.05), and the mRNA expression of IL-10 and p35 in the spleen of anti-TIM-4 group was significantly up-regulated(P<0.05), while EBi-3 mRNA expression was greatly down-regulated(P<0.05). Compared with the isotype control group, the proportion of peritoneal M1 macrophages and the p35 mRNA expression in the anti-TIM-4 group was not markedly changed (P>0.05), the proportion of M2 and the mRNA expression of IL-10, p40 and EBi-3 in peritoneal cavity were significantly increased, while miR-21 expression was remarkably decreased(P<0.05). Conclusion: Blockade of TIM-4 molecule may promote the proliferation and differentiation of M2 and up-regulate the mRNA expression levels of anti-inflammatory cytokines and pro-inflammatory cytokines in peritoneal and splenic cells, and reduce the allogeneic immune rejection response.

［Key words］T-cell immunoglobulin and mucin domain containing protein-4; M1/M2 macrophage; microRNA-21; cytokines; polarization; immune rejection