The Investigation Of Food Antigen-specific Serum Immunoglobulins G Antibodies And Dendritic Cells Of Colonic Mucosa In Patients With Irritable Bowel Syndrome With Diarrhea.

[Background and Aims]Irritable bowel syndrome(IBS)is a kind of common functional intestinal disorders.Some food could induce the symptoms of IBS,especially IBS with diarrhea(IBS-D).But its pathophysiology is unclear. Food intolerance is defined as food adverse reactions to some special foods or food components on human bodies including allergy,deficiency of enzyme, pharmacological action and other uncertain reasons.The immunology system of human body could produce specific immunoglobulins G(IgG)antibodies to some foods or many food components,and then form antigen-antibody complex which could damage many systems especially digestive system.Some investigations have showed that the incriminated foods of IBS-D could be reflected by checking serum food specific IgG antibodies.But the investigations were limited and the results were varied.So that we investigated the serum food specific IgG antibodies of IBS-D in order to know about its relationship with IBS-D.The antibodies' production had a close relationship with antigens stimulation and present.Dendritic cells(DCs)are powerful antigen-presenting cells and the only kind of immune cells which can stimulate the naive T cells.They can induce immune responses against harmful antigens as well as produce immune tolerance to the harmless antigens.DCs play an important role in the priming,regulation and maintenance of intestinal immune system.DCs might be responsible for IBS-D,but there have not investigations reported about it.The aim of our investigation was to find the possible change of DCs in colonic mucosa of IBS-D and their possible role in IBS-D.The results might find a new trial of the pathogenesis of IBS-D.[Materials and Methods]1,72 patients with IBS-D(45 M,27 F,average age 38.8±12.7years,RomeⅢcriteria)and 135 controls(80 M,55 F,average age 45.6±8.4 years)were recruited in this study.Serum IgG antibodies to 14 common foods including beef,chicken,codfish,corn,crab,eggs,mushroom, milk,pork,rice,shrimp,soybean,tomatoes and wheat were checked using the method of ELISA The positive rates of serum IgG antibodies to every kind of foods were calculated in two groups.The differential positive rate of food was selected and the relationship was analyzed between its semi-quantitive trires and the grade of symptom severity of IBS-D.The positive rate for≥1 kinds of foods standing for total positive rate was calculated in IBS-D groups and controls.We respectively calculated the positive rates for 1,2,≥3 kinds of foods between these two groups and compared with them.2,20 patients with IBS-D(16 M,4 F, average age 37.8±4.7 years,RomeⅢcriteria)and 20 controls(17 M,3 F, average age 40.2±6.3 years)were studied in the second investigation.Biopsies were performed from the ileocecal junction and sigmoid colon while doing colonoscopy examination,2-3 forceps pieces were taken respectively at each site. The specimens were stained with hematoxylin and esosin and marked CD11c using immunohistochemical techniques.The distribution of DCs in the colonic mucosal(original magnification×100)was observed and the numbers of DCs were counted.We counted the numbers of DCs in a minimum of 10 microscopic fields (×400)for samples from each person,couted the munbers of DCs and the total cells and got the numbers of DCs‰using the division formular.The results vere showed with mediam(qurtering range)‰.We compared the difference between these two groups.We analyzed the data with matholds of x~2,pearson's test or Kruskal-Wallis test by CHISS.Significant difference was accepted at 5% level(P＜0.05).[Results]The positive rate of serum IgG antibodies to eggs was 48.6%in IBS-D,it was much higher than controls which was 25.2%,(P=0.0007).No difference was found to the other 13 kinds of foods.No relationship was found between semi-quantitive trires of egg antigen-specific IgG antibodies and the grade of symptoms severity of IBS-D.The positive rate of serum IgG antibodies for≥3 kinds of foods was 34.7%,it was more than that of controls which was 20.7%(P=0.0281).DCs in the colonic mucosa were localized in the lamina propria and submucosa.The numbers of DCs in the ileocecal junction colonic mucosa of controls were 0.8(0.4)‰and IBS-D groups were 3(1.3)‰.The result was different(P=0.000.Numbers of DCs in the sigmoid colonic mucosa of controls were 0.5(0.2)‰and IBS-D groups were0.8(0.4)‰.The result was different(P=0.001).The numbers of DCs in the ileocecal junction colonic mucosa of these two groups were more than those of sigmoid colonic mucosa (P=0.001,P=0.000).[Conclusion]The positive rate of serum IgG antibodies to eggs and the positive rate of food antigen-specific IgG antibodies for≥3 kinds of foods were high in IBS-D.Our results showed that food intolerance might have a relationship with IBS-D.The numbers of DCs in the ileocecal junction and sigmoid colonic mucosa were significantly increased compared with controls.DCs in the colonic mucosa might play some role in the pathogenesis of IBS-D.