AIM: To investigate the effects of traditional Chinese medicinal enema (TCME) on inflammatory and immune response of colonic mucosa of rats with ulcerative colitis(UC), and to observe the pathogenic mechanism.METHODS: Thirty UC rats, induced by intestinal enema together with 2.4-dinitrochlorobenzene (DNCB) and acetic acid, were randomly divided into 3 groups, i.e., GⅠ, GⅡ and GⅢ. Groups GⅠ and GⅡ were administered with TCME and salazosulfapyridine enema (SASPE), respectively. Group GⅢwas clystered with only normal saline (NSE), served as control. Group GⅣ was taken from normal rats as reference,once daily, from the 7th day after the establishment of UC for total 28 d. Interleukin-6 (IL-6) in the colonic mucosa was assayed by 3H-TdR incorporation assay. Colonic mucosal lymphocyte subpopulation adhesive molecules, CD4+CD11a+,CD4+CD18+, CD8+CD11a+, CD8+CD18+ (LSAM), tumor necrosis factor (TNF)-α, and interferon-γ (IFN-γ), were detected by enzyme linked immunosorbent assay (ELISA). Moreover, the expression of TNF-α mRNA and IFN-γ mRNA in colonic mucosa were detected by polymerase chain reaction (RT-PCR).RESULTS: Before therapies, in model groups, GⅠ, GⅡ and GⅢ,levels of IL-6, TNF-α, IFN-γ CD8+CD11a+ and CD8+CD18+ were significantly different (38.29±2.61 U/mL, 16.54±1.23 ng/L,8.61±0.89 ng/L, 13.51±2.31% and 12.22±1.13%,respectively) compared to those in GIⅣ group (31.56±2.47U/mL, 12.81±1.38 ng/L, 5.28±0.56 ng/L, 16.68±1.41%and 16.79± 1.11%, respectively). After therapeutic enemas,in GI group, the contents of IL-6 (32.48±2.53 U/m), TNF-α(13.42±1.57 ng/L) and IFN-γ (5.87±0.84 ng/L) were reduced; then, the contents of CD8+CD11a+ (16.01±1.05 %)and CD8+CD18+ (16.28±0.19%) were raised. There was no significant difference between groups GⅠ and GⅣ, but the difference between groups GⅠ and GⅡ was quite obvious(P＜0.05). The expressions of TNF-α mRNA and IFN-y mRNA in group GⅢ were much higher than those of group GⅣ,but those in group GⅠ were significantly suppressed by TCME therapy.CONCLUSION: Ulcerative colitis is related to colonic regional mucosal inflammatory factors and immune imbalance. TCME can effectively inhibit regional mucosal inflammatory factors and improve their disorder of immunity.