The distribution of SIgA and IgG antibody-secreting cells in the large intestine of Bactrian camels (Camelus bactrianus).

Abstract

Mucosal immunoglobulin comprises mainly secretory immunoglobulin A (SIgA) which mainly participates in the intestinal mucosal pathogenspecific immune response. Immunoglobulin G (IgG) is another common immunoglobulin. Bactrian camels' gastrointestinal mucosal tissue has a special mucosal immune system. However, the distribution characteristics of these two antibody-secreting cells (ASCs) in Bactrian camel's large intestine mucosal immunity system remain largely unknown. This study was aimed to describe the distribution characteristics and density of SIgA and IgG ASCs in the mucosal immunity tissues of Bactrian camel large intestine. Tissue samples were collected from different parts of the large intestines of 10 healthy adult Chinese Alashan Bactrian camels. Immunohistochemistry technology was used to determine the distribution of SIgA and IgG ASCs in the large intestine samples and the image-Pro Plus 6.0 was employed to calculate their densities. SIgA and IgG ASCs were distributed in lamina propria of the large intestine mucosa with some ASCs aggregating around the intestinal glands. The SIgA density increased from ileocecal orifice to the caecum and decreased from the colon to the rectum. The largest number of SIgA ASCs was observed in the caecum, followed by anterior colonic segments, ileocecal orifice, posterior colonic segments, and rectum, and the number of SIgA ASCs in the caecum was significantly larger than that in other four positions (p < 0.05). Similarly, the number of IgG ASCs was also the largest in the caecum, which was significantly higher than that in ileocecal orifice, anterior, posterior colonic segments, and rectum (p < 0.05). Our findings suggest that SIgA and IgG ASCs are mainly distributed in intestinal mucosal immunity effector sites. These distribution characteristics provide evidence to support that SIgA and IgG supply effective protection and maintain homeostasis in the large intestinal mucosa.