title: Localization of neonatal Fc receptor for IgG in aggregated lymphoid nodules area in abomasum of Bactrian camels (Camelus bactrianus) of different ages.
abstract: BACKGROUND
  The neonatal Fc receptor (FcRn) plays a crucial role in transporting IgG and associated antigens across polarized epithelial barriers in mucosal immunity. However, it was not clear that FcRn expression in aggregated lymphoid nodules area (ALNA) in abomasum, a unique and important mucosal immune structure discovered only in Bactrian camels. In the present study, 27 Alashan Bactrian camels were divided into the following five age groups: fetus (10-13 months of gestation), young (1-2 years), pubertal (3-5 years), middle-aged (6-16 years) and old (17-20 years). The FcRn expressions were observed and analyzed in detail with histology, immunohistochemistry, micro-image analysis and statistical methods.
  
  
  RESULTS
  The results showed that the FcRn was expressed in mucosal epithelial cells of ALNA from the fetus to the old group, although the expression level rapidly declined in old group; moreover, after the ALNA maturated, the FcRn expression level in the non-follicle-associated epithelium (non-FAE) was significantly higher than that in FAE (P < 0.05). In addition, the FcRn was also expressed in the vessel endothelium, smooth muscle tissue, and macrophages and dendritic cells (DCs) of secondary lymphoid follicles (sLFs).
  
  
  CONCLUSIONS
  It was demonstrated that FcRn was mainly expressed in non-FAE, the effector sites, although which was expressed in FAE, the inductive sites for mucosal immunity. And it was also expressed in DCs and macrophages in sLFs of all ages of Bactrian camels. The results provided a powerful evidence that IgG (including HCAb) could participate in mucosal immune response and tolerance in ALNA of Bactrian camels through FcRn transmembrane transport.
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
authors.forename: Wang-Dong
authors.initials: WD
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, 730070, China. wwh777@126.com.
authors.forename: Wen-Hui
authors.initials: WH
authors.lastname: Wang
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
authors.forename: Shu-Xian
authors.initials: SX
authors.lastname: Li
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
authors.forename: Shuai
authors.initials: S
authors.lastname: Jia
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
authors.forename: Xue-Feng
authors.initials: XF
authors.lastname: Zhang
authors.affiliation: College of Veterinary Medicine, Gansu Agricultural University, Lanzhou, Gansu, 730070, China.
authors.forename: Ting-Ting
authors.initials: TT
authors.lastname: Cao
mesh_terms: D000018:Abomasum / Q000276:immunology* / Q000378:metabolism; D000367:Age Factors; D000818:Animals; D002162:Camelus / Q000276:immunology* / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D018928:Immunity, Mucosal / Q000235:genetics / Q000276:immunology*; D007074:Immunoglobulin G / Q000378:metabolism*; D008221:Lymphoid Tissue / Q000276:immunology* / Q000378:metabolism; D011961:Receptors, Fc / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism
chemical_list: D015395:Histocompatibility Antigens Class I; D007074:Immunoglobulin G; D011961:Receptors, Fc; C100688:Fc receptor, neonatal
keywords: Aggregated lymphoid nodules area (ALNA); Bactrian camels; Epithelium; Expression; Mucosal immunity; Neonatal Fc receptor (FcRn)