title: Mapping of the neonatal Fc receptor in the rodent eye.
abstract: OBJECTIVE
  The neonatal Fc receptor (FcRn) has been known to modulate IgG transport and protect against IgG catabolism, resulting in extension of the serum half-life of IgG. The goal of this study was to localize FcRn receptor expression in the rat's eye.
  
  
  METHODS
  The cornea, retina, conjunctiva, ciliary body and iris, retinal pigment epithelium and choroid, and lens were dissected from each rat's eye, and total RNA was purified. The first-strand cDNAs were synthesized and subjected to PCR reaction. For control samples, reverse transcriptase was omitted. A monoclonal antibody against the FcRn heavy chain was used to localize the distribution of the FcRn receptor in ocular tissues. Lymphatic vessels and blood vessels were stained with a rabbit anti-mouse lymphatic vessel endothelial receptor-1 polyclonal antibody and a rabbit anti-human von Willebrand factor polyclonal antibody, respectively.
  
  
  RESULTS
  RT-PCR demonstrated expression of FcRn RNA in cornea, retina, conjunctiva, ciliary body and iris, and lens but absence of expression in the retinal pigment epithelium and choroid. Immunohistochemistry and double staining confirmed the expression of FcRn receptor to the conjunctival lymphatic vessels but not in the conjunctival blood vessels. In the ciliary body, the FcRn receptor was found to be expressed in both the nonpigmented ciliary epithelium and the ciliary blood vessels. The expression of FcRn receptor was confirmed in the retinal blood vessels, iris blood vessels, optic nerve vascular structures, corneal epithelium and endothelium, and lens epithelium.
  
  
  CONCLUSIONS
  The FcRn receptor is expressed in multiple ocular tissues. The blood-ocular barrier showed FcRn receptor expression, indicating that IgG transport from ocular tissues to the blood system may use this receptor. The role of the FcRn receptor in the anterior segment and the conjunctiva remains unclear.
authors.affiliation: Department of Ophthalmology, Duke University Medical Center, 1530 Erwin, Durham, NC 27705, USA.
authors.forename: Hyuncheol
authors.initials: H
authors.lastname: Kim
authors.forename: Robert N
authors.initials: RN
authors.lastname: Fariss
authors.forename: Connie
authors.initials: C
authors.lastname: Zhang
authors.forename: Shaun B
authors.initials: SB
authors.lastname: Robinson
authors.forename: Michelle
authors.initials: M
authors.lastname: Thill
authors.forename: Karl G
authors.initials: KG
authors.lastname: Csaky
mesh_terms: D000818:Animals; D001808:Blood Vessels / Q000378:metabolism; D005123:Eye / Q000378:metabolism*; D015870:Gene Expression; D015395:Histocompatibility Antigens Class I / Q000235:genetics* / Q000378:metabolism; D042601:Lymphatic Vessels / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011961:Receptors, Fc / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015395:Histocompatibility Antigens Class I; D012333:RNA, Messenger; D011961:Receptors, Fc; C100688:Fc receptor, neonatal