Changes of CD8+CD28- T regulatory cells in rat model of colitis induced by 2,4-dinitrofluorobenzene

To determine the changes of CD8+ T subsets especially CD8+CD28- T regulatory cells in rat model of experimental colitis induced by 2,4-dinitrofluorobenzene (DNFB).

The rat model of experimental colitis was induced by enema with DNFB. Ten days later, colonic intraepithelial and splenic lymphocytes were isolated from colitis animals (n=16) and controls (n=8). The proportion of CD8+ T cells, CD8+CD28+ T cells and CD8+CD28- T regulatory cells were determined by flow cytometry.

The model of experimental colitis was successfully established by DNFB that was demonstrated by bloody diarrhea, weight loss and colonic histopathology. The proportion of CD8+ T cells in either splenic or colonic intraepithelial lymphocytes was not significantly different between colitis animals and controls (spleen: 34.6+/-7.24% vs 33.5+/-9.41%, colon: 14.0+/-8.93% vs 18.0+/-4.06%, P>0.05). But CD8+CD28- T regulatory cells from colitis animals were significantly more than those from controls (spleen: 11.3+/-2.26% vs 5.64+/-1.01%, colon: 6.50+/-5.37% vs 1.07+/-0.65%, P<0.05). In contrast, CD8+CD28+ T cells from colitis animals were less than those from controls (spleen: 23.3+/-6.14% vs 27.8+/-9.70%, P=0.06; colon: 7.52+/-4.18% vs 16.9+/-4.07%, P<0.05). The proportion of CD8+CD28- T regulatory cells in splenic and colon intraepithelial CD8+ T cells from colitis animals was higher than that from controls (spleen: 33.3+/-5.49% vs 18.4+/-7.26%, colon: 46.0+/-14.3% vs 6.10+/-3.72%, P<0.005).

Experimental colitis of rats can be induced by DNFB with simplicity and good reproducibility. The proportion of CD8+CD28- T regulatory cells in rats with experimental colitis is increased, which may be associated with the pathogenesis of colitis.