title: Local retention of soluble antigen by potential antigen-presenting cells in the anterior segment of the eye.
abstract: OBJECTIVE
  To determine the capacity of bone marrow-derived cells in the anterior segment of the eye to capture a fluorescence-labeled antigen (Ag) injected into the anterior chamber (AC).
  
  
  METHODS
  Uveal tract and corneoscleral tissues from Lewis rats were cultured in vitro, with or without FITC-dextran (4 microg/mL final concentration), for 48 hours and examined by confocal microscopy. To investigate antigen uptake in vivo 2 microL (20 microg) of Cascade Blue-labeled dextran (CB-Dx) was injected into the right AC of Lewis rats. The density of Ag-positive cells in the iris at 1, 3, 5, or 12 days after injection was examined by in vivo video fluorescence microscopy. The distribution and phenotype of Ag-positive cells in frozen and paraffin-embedded sections of ocular tissues and in iris wholemounts from animals killed at 24 hours and day 7 were analyzed by fluorescence and confocal microscopy.
  
  
  RESULTS
  In organ culture conditions numerous cells in the iris, ciliary body, choroid, and corneal limbus were capable of capturing fluorescence-labeled Ag. In vivo observations and microscopic examination of experimental eyes at days 1 and 7 after AC injection revealed Ag-positive cells within the iris, iridocorneal angle, the suprachoroidal space and around limbal-episcleral vessels. Ag-bearing cells in the iris express combinations of macrophage markers but rarely expressed major histocompatibility complex (MHC) class II molecules. A reduced number of Ag-bearing cells were still present in the iris at day 12.
  
  
  CONCLUSIONS
  Potential antigen-presenting cells (APCs) in the iris and ciliary body are capable of internalizing intracameral Ag. The characteristics of these cells in the iris are consistent with a predominantly macrophage phenotype. These observations also suggest that the Ag leaving the eye through both the conventional and nonconventional aqueous outflow pathways may be captured by potential APCs in the episcleral tissues.
authors.affiliation: School of Anatomy and Human Biology, The University of Western Australia, Crawley (Perth), Western Australia 6009, Australia.
authors.forename: Serge
authors.initials: S
authors.lastname: Camelo
authors.forename: Angel S P
authors.initials: AS
authors.lastname: Voon
authors.forename: Stuart
authors.initials: S
authors.lastname: Bunt
authors.forename: Paul G
authors.initials: PG
authors.lastname: McMenamin
mesh_terms: D000818:Animals; D000869:Anterior Eye Segment / Q000378:metabolism*; D000938:Antigen-Presenting Cells / Q000378:metabolism; D000941:Antigens / Q000378:metabolism*; D002829:Choroid / Q000166:cytology; D002924:Ciliary Body / Q000166:cytology; D003713:Dendritic Cells / Q000378:metabolism*; D003911:Dextrans / Q000378:metabolism; D005260:Female; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000378:metabolism; D016130:Immunophenotyping; D007498:Iris / Q000166:cytology; D016850:Limbus Corneae / Q000166:cytology; D008264:Macrophages / Q000378:metabolism*; D018613:Microscopy, Confocal; D008856:Microscopy, Fluorescence; D009924:Organ Culture Techniques; D051381:Rats; D011917:Rats, Inbred Lew
chemical_list: D000941:Antigens; D003911:Dextrans; C015219:fluorescein isothiocyanate dextran; D016650:Fluorescein-5-isothiocyanate