Objective To explore the role and mechanism of protein disulfide isomerase A3 (PDIA3) in abnormal colonic mucosa immune response of irritable bowel syndrome (IBS) rats with visceral hypersensitivity. Methods A total of 48 SD rats were divided into blank control group (n=12), empty virus group (IBS-1) (n=12), PDIA3 silencing group (IBS-2) (n=12) and model control group(IBS-3) (n=12). The expression of CD103 in ileocecus colonic tissues was detected by immunohistochemistry. Dendritic cells (DC) of mesenteric lymph node were isolated by flow cytometry. CD4+ /CD8+ T cells of spleen were separated by immune-magnetic beads sorting technique. DC and CD4+ /CD8+ T cells were co-cultured. The proliferation ability of lymphocytes promoted by DC was measured by methyl thiazolyl tetrazolium (MTT). The secretion levels of interlcukin (IL)-4 and IL-9 of CD4+ /CD8+ T cells stimulated by DC were determined by enzyme linked immunosorbent assay (ELISA) method. Independent sample t-test was performed for statistical analysis. Results The cell number of CD103 positive DC of rats colon of blank control group, IBS-3 group was 6.25±1.14 and 10.83±1.03(t=10.07, P<0.05); that of IBS-2 group was 7.42±0.90, and compared with that of IBS-3 group, the difference was statistically significant (t=-9.25, P<0.05). The MTT value of CD4+ T cells proliferation stimulated by DC of blank control group and IBS-3 group was 0.54±0.01 and 0.60±0.01(t=3.373, P<0.05); that of IBS-2 group was 0.53±0.01, and compared with that of IBS-3 group, the difference was statistically significant (t=-3.139, P<0.05). The MTT value of CD8+ T cells proliferation stimulated by DC was 0.52±0.01 and 0.59±0.00(t=3.539, P<0.01); that of IBS-2 group was 0.54±0.01, and compared with that of IBS-3 group, the difference was statistically significant (t=-3.183, P<0.05). The level of IL-4 secreted by CD4+ T cells promoted by DC of blank control group and IBS-3 group was 10.24±0.09 and 16.61±1.00 (t=3.222, P<0.05); that of IBS-2 group was 11.75±0.54, and compared with that of IBS-3 group, the difference was statistically significant (t=-3.539, P<0.01). The level of IL-9 secreted by CD4+ T cells stimulated by DC of blank control group and IBS-3 group was 15.86±10.19 and 43.51±11.32 (t=4.529, P<0.05); that of IBS-2 group was 29.05±2.09, and compared with that of IBS-3 group, the difference was statistically significant (t=-6.841, P<0.01). The level of IL-4 secreted by CD8+ T cells promoted by DC of blank control group and IBS-3 group was 7.35±0.12 and 13.91±0.57 (t=19.557, P<0.01); that of IBS-2 group was 8.63±0.24, and compared with that of IBS-3 group, the difference was statistically significant (t=-14.782, P<0.01). The level of IL-9 secreted by CD8+ T cells stimulated by DC of blank control group and IBS-3 group was 29.12±5.14 and 60.70±11.02 (t=4.122, P<0.05); that of IBS-2 group was 37.17±2.65, and compared with that of IBS-3 group, the difference was statistically significant (t=-3.255, P<0.05). Conclusions Protein disulfide isomerase A3 may mediate the process of DC activating T lymphocyte levels of related cytokines, cause abnormal immune response of colonic mucosa and promote the genesis of IBS visceral hypersensitivity. Key words: Protein disulfide isomrase A3; Dendritic cells; Interleukin-4; Interleukin-9; CD4-positive T-lymphocytes; CD8-positive T-lymphocytes; Visceral hypersensitivity