Moniezia benedeni infection increases IgE⁺ cells in sheep (Ovis aries) small intestine

The concentration of immunoglobulin (Ig) E is the lowest among serum Igs, but it can induces type I hypersensitivity and plays an important role in anti-parasitic infection. The present study aimed to explore the residence characteristics of IgE⁺ cells in the sheep small intestine and the impact of Moniezia benedeni infection on them. The recombinant plasmids pET-28a-IgE were constructed and induced and expressed in Escherichia coli. BL21 (DE3). The rabbit anti-sheep IgE polyclonal antibody was prepared using the obtained recombinant protein as antigen. Finally, the levels of IgE⁺ cells in the small intestine of healthy (Control group) and naturally M. benedeni-infected (Infected group) sheep were detected analyzed. The results showed that the rabbit anti-sheep IgE polyclonal antibody with good immunogenicity (titer = 1: 128000) could specifically bind to the heavy chain of natural sheep IgE. In the Control group, the IgE⁺ cells were mainly distributed in lamina propria of the small intestine, and the densities were significantly decreased from duodenum to ileum (P<0.05), with respective values of (4.28 cells / 10⁴ μm², 1.80 cells / 10⁴ μm², and 1.44 cells / 10⁴ μm² in duodenum, jejunum, and ileum. In the Infected group, IgE⁺ cells density were 6.26 cells / 10⁴ μm², 3.01 cells / 10⁴ μm², and 2.09 cells / 10⁴ μm² in duodenum, jejunum and ileum respectively, which were significantly higher in all segments compared to the Control group (P<0.05), increasing by 46.26%, 67.22% and 45.14%, respectively. In addition, compared with the Control group, the IgE protein levels were significantly increased in all intestinal segments of the Infected group (P<0.01), however, there was no significant differences among the different intestinal segments within the same group (P>0.05). The results demonstrated that M. benedeni infection could significantly increase the content of IgE and the distribution density of its secreting cells in sheep small intestine. The intestinal mucosal immune system of sheep presented obvious specificity against M. benedeni infection. This lays a good foundation for further exploring molecular mechanisms of the intestinal mucosal immune system monitoring and responding to M. benedeni infection.