An Experimental Study On The Detection Of APCs Of Cornea With Rejection After Penetrating Keratoplasty In Comparison With ACAID In Rats

Background: Penetrating keratoplasty is the oldest and one of the most successful forms of solid tissue transplantation. However, the allograft rejection is the major factor of the failure for it. The allograft corneal rejection has been certified as delayed hypersensitivity activated by CD4+ T cells. Besides, there is another phenomena occurs at the anterior chamber of the eye that is termed anterior chamber-associated immune deviation (ACAID). Injection of antigen into the anterior chamber of the eye dramatically alters the systemic immune response to specific Ag, which is characterized by impairment of delayed hypersensitivity. To the same Ag, such as alloantigen, how does the immune response of the recipient develop? Current dogma holds that the antigen-presenting cells (APCs) play a critical role in deciding the direction of the immune response: rejection or acceptance. Dendritic cells (DCs) are a minor population of bone marrow-derived leukocytes that are the most effective APCs for activation of T cells. DCs are not only critical for the induction of primary immune response, but also are important for the induction of immunological tolerance. This regulation function seems to be associated with a characteristic phenotype. CD86 is one of the signal transmission molecules that expressed on the surface of APCs. CD86 and its receptors expressing in T cells interact to transmit costimulatory signal to activate CD4+T cells to induce immune response. So CD86 is thought as the mature marker of APCs. OX-62 antigen, as a special marker of DCs of rats, that expresses on the surface of DCs maybe the mature marker too. Therefore, researches on the expression of CD86 and the examination of DCs (labeled by OX-62 antibody) of cornea are helpful to study the immunopathologic process of rejection to prevent the corneal graft rejection and understand the mechanism of ACAID.In the present study, we performed this experiment to detect theexpression of CD86 and the examination of DCs of cornea during the acute immune rejection in experiment penetrating keratoplasty as well as AC AID in rats. Objectives:1. To investigate the expression of CD86 and OX-62 of cornea in situ in normal rats.2. Study on the expression of CD86 and OX-62 of the corneal allografts during the acute immune rejection in experiment penetrating keratoplasty in rats and to analysis the roles of CD86+ cells and OX-62+DCs in the corneal allograft rejection.3. Study on the expression of CD86 and OX-62 of cornea after ACAID induced by injection of splenocytes from the same rat donor into the anterior chamber of the eye and to analysis the roles of CD86+ cells and OX-62+DCs in ACAID.Methods:Rats were randomly assigned to there groups: The group I were normal as control; Corneal transplantation were performed orthotopically from Wistar rats to SD rats' recipients in the group II; The group III were induced by injection of splenocytes from the same rat donor into the anterior chamber of the eye. Rejection index was determined at the group II. DTH responses to alloantigen were evaluated by measuring an ear swelling at the group III (DTH responses to the donor alloantigen were examined in normal rats as positive control). The corneas of those rats were enucleated at different time. The immunohistochemistry staining was adopted to examine the expression of CD86 and OX-62 on the cornea whole-mounts as well as the spleen tissue as positive control. Results:1. There were not CD86+cells and OX-62+DCs in the normal cornea .2. They were present at the epithelium of cornea during allograft rejection at group II and the rate of acute rejection is 100%.3. At group III: The ACAID had been induced successfully at 2 or 4weeks after injection of splenocytes into the anterior chamber of the eyes. There were not CD86+cells and OX-62+DCs detected in corneal epithelia of rats of ACAID, too, however there were some CD86+cells and OX-62+DCs in the peripheral epithelium of cornea. Conclusions:1. There were not mature APCs in the norm...