Tfh Cell Regulates Autoantibody To Initiate Intestinal Inflammation In Immune-complex Induced Colitis

Objectives This study aimed at detecting the changes of Tfh cell numbers, plasma cell numbers, the titers of autoantibody and relative cytokines to investigate the effects of Tfh cell regulate the autoantibody formation in immune-complex induced colitis.Methods Twelve male BALB/C mice were randomly divided into two groups:control group and model group. Model group was given immune complex subcutaneous and intraperitoneal injection respectively on day0,7,14and21. Then intracolonic administration of TNBS in50%ethanol on day28. The mice of control group were treated with an equal volume of saline at the same time. All of the mice were sacrificed on day42, and the inflammation of colon was assessed by the HE dyeing as well as MPO activity assay. Changes of the Tfh and plasma cell numbers were detected by flow cytometry. The expession of IL-21and Bcl-6mRNA in colon mucosa were determined by RT-PCR. We also used Elisa to detect the titers of the autoantibodies in serum.Result MPO activity of model group(0.4543U/g±0.12207U/g) were significantly increased, compared with mice of control group(0.3127U/g±0.06983U/g,p<0.05). Tfh and plasma cell numbers are1.550%±0.414%and0.780%±0.360%, significantly increased compared with control(1.000%±0.108%,0.300%±0.063%,p<0.05). IgG level of serum in control was7.94ng/ml±26.356ng/ml. And the IgG level in the model group was372.3ng/ml±43.925ng/ml, which was significantly increased(p<0.05). The expressions of Bcl-6mRNA and IL-21mRNA in colon mucous of model group were3.87+2.54and18.40±7.52, which were3.87and18.4times that of the control group(1.00±0.00,1.00±0.00), respectively. The differences are significant.Conclusion Tfh cell numbers, plasma cell numbers, the titers of autoantibody and relative cytokines were all up-regulated in immune-complex induced colitis. It shows that Tfh cell regulates autoantibody and plays an important role in the pathogenesis of colitis.