T cells of the colonic mucosa in patients with infantile colitis

Background: Infantile colitis is a heterogeneous group of disorders, includ ing enterocolitis complicating Hirschsprung disease, allergic colitis, infl ammatory bowel disease, and Behcet syndrome. There are limited data concern ing the immune responses induced by the inflammation of the intestine in yo ung infants. Methods: Twenty-four colonic biopsy specimens from 12 infantile colitis pat ients and 12 age-matched control patients were studied by immunohistologic methods. The authors compared the T cells, their subsets expressing the sur face antigens CD8 and CD4, and T-cell receptors alpha beta and delta gamma, and densities of mononuclear and epithelial cells expressing human leukocy te antigen class H antigens. Results: The density of CD3(+) intraepithelial lymphocytes (IELs) in the la rge intestinal specimens was significantly higher (P = 0.036) in colitis pa tients than in the control group. The majority of the CD3(+) IELs were CD8( +)-expressing cells, and only a minority were CD4(+) cells in both groups. T-cell receptors alpha beta (+) (P = 0.023) and delta gamma (+) (P = 0.027) IELs were observed significantly more frequently in colitis patients than in the control group. In surface epithelium, delta non-disulphide-linked ty pe T-cell receptor (delta TCS1) IELs were found strikingly more frequently (P = 0.001) in the specimens taken from the colitis patients. Also, the den sity of the delta TCS1+ cells in crypts of the large intestine was signific antly higher in colitis patients than in the control patients (P = 0.047). Conclusions: A significant increase of CD3(+) lymphocytes in the colonic ep ithelium of the patients with infantile colitis was noted. This increase in volved both T-cell receptor up-positive and delta gamma -positive IELs. The finding of this study supports the proposal that intraluminal antigens, ei ther microbial or food derived, are important in the pathogenesis of coliti s in young infants.