Immunity cells in the small intestinal mucosa of newborn yaks.

Background: This study aimed to characterize and evaluate the main markers of T lymphocytes, B lymphocytes, immunoglobulin (Ig) A and IgG plasmocytes, macrophages, and dendritic cells of the intestinal mucosa of newborn yaks. Materials and methods: Ten newborn yaks (2–4 weeks old) were choosed. Immunohistochemistry and real-time quantitative polymerase chain reaction were used to analyze the immune cell distribution and specific markers at the mRNA expression level in the duodenum, jejunum, and ileum. Results: The results showed in the epithelium, CD3-positive T lymphocyte levels were higher than other immune cell levels (P<0.05). Additionally, in the lamina propria, the number of cells positive for CD3, CD68, and signal inhibitory regulatory protein alpha (SIRPα) were higher in the villi, while CD79α, IgA, and IgG cells were more common at the base of the crypt. Moreover, both in the epithelium and lamina propria, the number of CD3, CD68 and SIRPα were decreased from the duodenum to the ileum (P<0.05), additionally the number of CD79α, IgA and IgG positive cells were increased from the duodenum to the ileum of newborn yaks (P<0.05). Furthermore, the mRNA expression levels of CD3e, CD68, and SIRPα increased from the duodenum to the ileum (P<0.05), while the mRNA expression levels of CD79α, IgA, and IgG decreased from the duodenum to the ileum. Conclusions: Immunohistochemical characterization and expression levels of immune factors in the small intestinal mucosa of newborn yaks suggest that the intestinal mucosa is an important part of the natural barrier and provides useful references for immunity functions of newborn yak intestinal mucosa.