Cell-mediated immune reaction to colon altered by bacteria

Decreased suppressor cell activity in inflammatory bowel disease

Studies were performed on eleven patients with inflammatory bowel disease to determine if there was an alteration in concanavalin A (Con A) induced suppressor cell activity. Similar investigations were also performed on twenty-one control subjects and five patients with other inflammatory conditions. Supressor cells were generated by pre-incubation of peripheral blood mononuclear cells with a mitogenic concentration of Con A, followed by treatment with mitomycin C and alpha-methyl mannoside. Under these conditions, cells obtained from normal individuals are then capable of suppressing the Con A-stimulated blast transformation responses of fresh allogeneic lymphocytes in new cultures. We found that in twenty out of twenty-one control subjects, and all five patients with other inflammatory disorders, Con A-stimulated suppressor cell activity was demonstrable. Four patients with inflammatory bowel disease, whose disease was mildly active or was in clinical remission, had elicitable suppressor cell activity which fell within the normal range. In contrast, suppressor cell activity was markedly diminished or absent in seven patients with severe and active inflammatory bowel disease. These studies suggest that an alternation in Con A-stimulated suppressor cells exists in patients with active inflammatory bowel disease, which may contribute, in part, to the persistent inflammation in the gastrointestinal tract.

Experimental colitis in rabbits

Experimental colitis was induced in rabbits either by immunizing the antigens which possess the cross-reacting antigenicity with colonic mucosa, and by infusing intravenously their own lymphocytes sensitized with E. coli 014 endotoxin which may contain a high concentration of common antigen (Kunin antigen). The hemorrhagic inflammatory changes were developed in the colon as follows; (1) three of fifteen rabbits immunized with rat colon, (2) one of three rabbits with their own E. coli, (3) six of fifteen rabbits with E. coli 014 and, (4) five of eight rabbits by infusing their own lymphocytes sensitized with E. coli 014 endotoxin. It was suggested that the cross-reacting antigenicity with the colonic mucosa and the sensitized lymphocytes implicate in the pathogenesis of chronic ulcerative colitis.

Lymphoblastic response to autologous colon epithelial cells in ulcerative colitis in vitro

The blastic transformation in vitro of peripheral blood lymphocytes was measured by the 72-hour uptake of tritiated thymidine ((3)H-6-thymidine) in 23 patients with mucosal ulcerative colitis, three patients with acute Crohn's colitis with rectal involvement, and seven normal subjects. The 23 patients with ulcerative colitis were subdivided into three groups, graded according to severity into seven with acute, severe, nine with active, chronic, and seven with quiescent disease. In the control cultures of lymphocytes without any added potential stimulant the uptake of (3)H-6-thymidine in the clinical subgroup of seven patients with acute, severe ulcerative colitis was significantly greater than in seven normal subjects (p<0.01). This contrasted with a reduced uptake of (3)H-6-thymidine by lymphocytes from seven patients with acute severe colitis when compared with seven normal subjects after stimulation with phytohaemagglutinin-P (PHA-P) (p<0.01). In further duplicate cultures of lymphocytes specifically stimulated by an equal number of viable autologous rectal epithelial cells, the uptake of (3)H-6-thymidine was significantly greater in seven patients with acute severe colitis when compared with seven normal subjects (p<0.01). The results in three patients with acute Crohn's colitis with rectal involvement showed no such evidence of lymphocyte sensitivity to autologous rectal epithelial cells and their uptake of (3)H-6-thymidine lay within the normal range.Evidence that the degree of lymphoblastic transformation was related to the clinical severity of ulcerative colitis was provided by the results obtained in the unstimulated and epithelial cell stimulant cultures. The uptake of (3)H-6-thymidine was directly related to the clinical severity of ulcerative colitis in the three subgroups studied. In addition, four of the seven patients with acute severe colitis were studied later in clinical remission. They were then found to have a significantly reduced uptake of (3)H-6-thymidine in response to autologous rectal epithelial cells (p < 0.01).