Susceptibilty of murine corneal kpithklial and endothelial cells to lysis by complement-dependent alloantibody

Purpose. To determine if orthotopic corneal allografts stimulated the production of allospecific cuotoxic antibody and if comeal epithelial and endothelial cells are vulnerable to K sis by complement-dependent antibody. Methods. The capacity of orthotopic corneal alIngrafts to induce allospecific antibody was determined by transplanting C3H/Hej (H-2k) corneal grafts onto CB6FI (H-2h'd) mice. Grafted mice were bled 30 days later and the serum tested by ELISA for the presence of anti-C3H/Hej alloantibody. Anti-C3H alloantiserum was prepared by immunizing CB6F1 (H-2 ) mice with two intramuscular injections of 5x10 allogeneic C3H/Hej {H-2 ) spleen cells. Complement-dependent antibody-mediated lysis of C3H corneal epithelial cells and C3H corneal endothelial cells was determined in a conventional in vitro 4-hr " Cr-release assay in the presence and absence of 50% human aqueous humor (AH). Results. Orthotopic corneal allografts induced significant allospecific IgG antibody production in 5 of 7 animals tested (P<0.05). in three separate experiments, hyper-immune anti-C3H/Hej serum produced 21% to 50% cytolysis of C3H/Hej corneal endothetial cells. By contrast, the same antiserum failed to l\se OH/Hej corneal epithelial cells. Antibody-mediated lysis of comeal epithelial cells could be inhibited b> the addition of 50% human AH. Conclusions. Although orthotopic corneal allografts can elicit the production of alloantibodies. comeal epithelial cells are resistant to antibody-mediated lysis. The resistance to lysis by complement-dependent antibody is presumably due to the expression of complement decay accelerating factor (DAF) on the corneal epithelium. By contrast, murine corneal endothetial cells do not express DAF and as a result are susceptible to complement-mediated lysis. However, DAF present in the AH protects corneal endothelial cells from injury inflicted by complement dependent cytolytic antibody.