The behaviour of ED1- and ED2-positive cells in the rat iris and choroid following penetrating keratoplasty and cyclosporin A therapy.
BACKGROUND
The presence, morphology and distribution of ED1 and ED2+ cells have been recently reported in detail in the uveal tissues of the rat. These cells, particularly those of dendritic morphology, are possibly capable of antigen presentation and, therefore, may play an important role in immune processes of uveal and other ocular tissues. Using the whole-mount technique, the distribution of ED1+ and ED2- cells in the rat iris and choroid was investigated following penetrating keratoplasty (PKP) and following treatment with cyclosporin A (CsA).


METHODS
Lewis (LW) rats received corneal buttons from Lewis-Brown Norway (LW-BN) donors and were randomly assigned to one of two groups: (I) operated, untreated (n = 24); (II) operated, CsA treated (10 mg/kg i.m.: n = 22). Four groups served as controls: normal LW rats (n = 13); (IV) unoperated, CsA treated (16 days' treatment; n = 8); (V) eight corneal sutures only, representing a simulated or "sham" operation (n = 4); (VI) syngeneic operated (LW to LW: n = 4). Animals of groups I and II were killed on the 5th, 9th and 13th postoperative days and on appearance of the corneal rejection (group I, day 13; Group II, day 16). Both eyes were enucleated, immediately fixed, and iris-choroid flat mounts were examined for ED1+ and ED2+ cells using APAAP immunohistochemistry.


RESULTS
In the normal LW rat iris, ED1+ and ED2+ cells of both non-dendritic and dendritic morphology were observed. The placement of sutures in the cornea and PKP with or without treatment resulted in a reasonably regular response in both the iris and the choroid in the operated and partner eye. These included: (a) an increase in round iridal ED1+ and ED2+ cells in the operated eye and in round ED1+ cells in the partner eye; (b) a decrease in dendritiform ED2+ cells in the iris of the operated eyes as well as in the partner eye; and (c) a decrease in the dendritiform ED2+ cells in the choroid of the operated and partner eye. CsA treatment alone in unoperated animals resulted in significant decreases in the number of dendritiform ED1+ cells in the iris and in the dendritiform ED2+ cells in the choroid.


CONCLUSIONS
Corneal transplantation in the Lewis rat results in responses in ED1+ and ED2+ cells in uveal tissues in both the operated eye as well as in the partner eye. The differences in cell behaviour supports the idea that distinct immune-competent cell populations are present within uveal tissues and that they may have differing roles in the pathological eye.
Krause
L
L
Eye Department, Universitätsklinikum Benjamin Franklin, Berlin, Germany.
Coupland
S E
SE
Hoffmann
F
F
D000818:Animals; D002452:Cell Count; D002829:Choroid / Q000276:immunology*; D016572:Cyclosporine / Q000627:therapeutic use*; D003713:Dendritic Cells / Q000276:immunology*; D005260:Female; D006084:Graft Rejection / Q000517:prevention & control; D000949:Histocompatibility Antigens Class II / Q000276:immunology; D007150:Immunohistochemistry; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D007498:Iris / Q000276:immunology*; D015948:Keratoplasty, Penetrating; D008264:Macrophages / Q000276:immunology*; D009000:Monocytes / Q000276:immunology*; D011897:Random Allocation; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew
D000949:Histocompatibility Antigens Class II; D007166:Immunosuppressive Agents; D016572:Cyclosporine