Diabetes-prone BioBreeding rats do not have a normal immune response when weaned to a diet containing fermentable fibre.

Diet is known to modulate the development of diabetes in diabetes-prone BioBreeding (BBdp) rats. The objective of the present study was to determine the effect of fermentable fibre (FF) on immune function in BBdp and diabetes-resistant BioBreeding (BBdr) rats after weaning. Weanling BBdp (thirty-six to thirty-eight per diet) and BBdr rats (thirty to thirty-two per diet) were fed a nutritionally complete, semi-purified, casein-based diet containing either cellulose (control diet, 8 % w/w) or FF (3.2 % cellulose+4.8 % w/w inulin). At 35 d, the small intestine was excised and lymphocytes isolated from spleen, mesenteric lymph nodes and Peyer's patches. Feeding FF to both BBdr and BBdp rats affected the production of anti-inflammatory cytokines (P=0.02). In BBdr rats, feeding FF compared with cellulose resulted in an increased small intestinal length (P=0.0031), higher proliferative (stimulation) index from both splenocytes (P=0.001) and mesenteric lymph nodes (P=0.04), and an increased proportion of CD8+ T-cells in the Peyer's patches (P=0.003). We did not observe an effect of diet on the number of IgA-bearing cells in the jejunum from BBdr rats. Feeding FF to BBdp rats did not affect the same parameters. BBdp rats had both a higher proportion of B-cells in the Peyer's patches (P=0.01) and a higher number of IgA+ cells in the jejunum (P=0.0036) when fed a diet containing FF, a response not observed in BBdr rats. We demonstrate that several aspects of the BBdp immune system respond differently than that of BBdr rats when challenged at weaning with FF.