IgA gene expression and quantification of mucous IgA+, IgM+ and CD4+ lymphocytes in the cecum of chicks was studied by qRT-PCR, immunohistochemistry and flow cytometry. A total of 220 1-day-old Salmonella-free chicks of Cobb 500 were divided into four groups (n=55). Group 1 served as control (C), group 2 was pretreated with probiotic bacterial strain Enterococus faecium AL41 (EFAL41), group 3 was infected with Salmonella Enteritidis PT4 (SE), and group 4 was pretreated with E. faecium AL41 and subsequently challenged with Salmonella Enteritidis PT4 (EFAL41+SE). The relative mRNA expression of IgA was upregulated in the EFAL41 group (P<0.05) when compared to control group at 4dpi. In comparison to the control, EFAL41 and SE group, the relative mRNA expression of IgA was also upregulated in EFAL41+SE group at 7dpi (P<0.001). Immunohistochemistry revealed, that the density of IgA+ cells was higher in EFAL41+SE group comparing to the controls and SE groups (P<0.001). Significantly more CD4+ cells were present in the SE group than in EFAL41 (P<0.05), and EFAL41+SE groups (P<0.001) at 4dpi. In contrast, higher density of CD4+cells at 7dpi was seen in EFAL41+SE group as compared with controls (P<0.05). Flow cytometry determined that relative percentage of intraepithelial lymphocytes (IEL) IgA+ cells was higher in EFAL41 than in SE and EFAL41+SE groups (P<0.05). Comparing to controls the number IgM+ cells increased in SE group (P<0.05) at 7dpi. The results demonstrated beneficial effect of E. faecium AL41 on the mRNA expression of IgA and number of IgA+ cells. Lamina propria lymphocytes (IgA+, IgM+) were not affected by EFAL41 intake or salmonella infection. Probiotic bacterial strain EFAL41 positively influenced the number of IEL during the first days of infection.
【저자키워드】 Lymphocytes, cecum, chicken, Enterococcus faecium, Salmonella infection,