T cells of the colonic mucosa in patients with infantile colitis

Infantile colitis is a heterogeneous group of disorders, including enterocolitis complicating Hirschsprung disease, allergic colitis, inflammatory bowel disease, and Behçet syndrome. There are limited data concerning the immune responses induced by the inflammation of the intestine in young infants.

Twenty-four colonic biopsy specimens from 12 infantile colitis patients and 12 age-matched control patients were studied by immunohistologic methods. The authors compared the T cells, their subsets expressing the surface antigens CD8 and CD4, and T-cell receptors alphabeta and deltagamma, and densities of mononuclear and epithelial cells expressing human leukocyte antigen class II antigens.

The density of CD3+ intraepithelial lymphocytes (IELs) in the large intestinal specimens was significantly higher (P = 0.036) in colitis patients 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 alphabeta+ (P = 0.023) and deltagamma+ (P = 0.027) IELs were observed significantly more frequently in colitis patients than in the control group. In surface epithelium, delta non-disulphide-linked type T-cell receptor (deltaTCS1) IELs were found strikingly more frequently (P = 0.001) in the specimens taken from the colitis patients. Also, the density of the deltaTCS1+ cells in crypts of the large intestine was significantly higher in colitis patients than in the control patients (P = 0.047).

A significant increase of CD3+ lymphocytes in the colonic epithelium of the patients with infantile colitis was noted. This increase involved both T-cell receptor alphabeta-positive and deltagamma-positive IELs. The finding of this study supports the proposal that intraluminal antigens, either microbial or food derived, are important in the pathogenesis of colitis in young infants.