title: Retinal pigment epithelial cells phagocytosis of T lymphocytes: possible implication in the immune privilege of the eye.
abstract: OBJECTIVE
  To investigate the capability of retinal pigment epithelium (RPE) cells to phagocytose T lymphocytes and to further analyse the immunobiological consequences of this phagocytosis.
  
  
  METHODS
  Human RPE cells pretreated or not by cytochalasin, a phagocytosis inhibitor, were co-cultured with T lymphocytes for different time points. Phagocytosis was investigated by optic microscopy, electron microscopy, and flow cytometry. T cell proliferation was measured by (3)H thymidine incorporation. RPE interleukin 1beta mRNA expression was quantified by real time PCR.
  
  
  RESULTS
  RPE cells phagocytose apoptotic and non-apoptotic T lymphocytes, in a time dependent manner. This is an active process mediated through actin polymerisation, blocked by cytochalasin E treatment. Inhibition of RPE cell phagocytosis capabilities within RPE-T cell co-cultures led to an increase of lectin induced T cell proliferation and an upregulation of interleukin 1beta mRNA expression in RPE cells.
  
  
  CONCLUSIONS
  It is postulated that T lymphocyte phagocytosis by RPE cells might, by decreasing the total number of T lymphocytes, removing apoptotic lymphocytes, and downregulating the expression of IL-1beta, participate in vivo in the induction and maintenance of the immune privilege of the eye, preventing the development of intraocular inflammation.
authors.affiliation: Interdisciplinary Research Institute (IRIBHN), Université Libre de Bruxelles, Belgium. fwillermain@hotmail.com
authors.forename: F
authors.initials: F
authors.lastname: Willermain
authors.forename: L
authors.initials: L
authors.lastname: Caspers-Velu
authors.forename: B
authors.initials: B
authors.lastname: Nowak
authors.forename: P
authors.initials: P
authors.lastname: Stordeur
authors.forename: R
authors.initials: R
authors.lastname: Mosselmans
authors.forename: I
authors.initials: I
authors.lastname: Salmon
authors.forename: T
authors.initials: T
authors.lastname: Velu
authors.forename: C
authors.initials: C
authors.lastname: Bruyns
mesh_terms: D000199:Actins / Q000032:analysis; D002455:Cell Division; D002478:Cells, Cultured; D003572:Cytochalasins / Q000494:pharmacology; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007111:Immunity, Cellular; D007375:Interleukin-1 / Q000032:analysis; D008854:Microscopy, Electron; D010587:Phagocytosis / Q000187:drug effects; D010857:Pigment Epithelium of Eye / Q000166:cytology / Q000276:immunology / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013601:T-Lymphocytes
chemical_list: D000199:Actins; D003572:Cytochalasins; D007375:Interleukin-1; D012333:RNA, Messenger; C007215:cytochalasin E