Article ID: 0120134
The aim of this study was to determine the effects of probiotics on T cell subsets induction in the intestine of broiler chicks. Day-old male broiler chicks were fed with or without probiotics consisting of Streptococcus faecalis, Clostridium buthricum, Bacillus mesentericus (probiotics group and control group, respectively). Cryostat sections of their ileum, cecum and rectum at day 0, 7 and 14 of feeding were immunostained for CD4, CD8 and TCRγδ, and the frequencies of positive cells in the mucosal tissue were analyzed. The CD4+, CD8+, TCRγδ+ T cells were localized in the lamina propria of intestinal mucosa in all birds. At day 7 and 14, CD8+ T cells were localized also in the mucosal epithelium of all segments in the probiotics group and of cecum in control group, and TCRγδ+ T cells were observed in the mucosal epithelium of all birds. The frequencies of CD4+, CD8+, TCRγδ+ T cells were increased with age from day 0 to day 14 in both control and probiotics groups. The frequency of CD8+ T cells was significantly greater in probiotics group than control group in the ileum and rectum (P< 0.05) and the cecum (P< 0.01) at day 7. There were no significant differences in the frequency of CD4+ and TCRγδ+ T cells between control and probiotics groups in all intestinal segments at day 7 and 14. The ratio of CD8+/CD4+ T cells was greater than 1.0 in all tissues. The ratio in the ileum at day 7 was significantly greater in the probiotics group than control group (P<0.05). These results further suggest that probiotics cause an influx of the CD8+ T cells into the intestinal mucosa, which may enhance the intestinal immunity by CD8+ T cells in young chicks.