Aim: To investigate if the immunological tolerance induced by superantigen staphylococcus enterotoxin B (SEB) takes part in the reaction at the immune privileged site.
Methods: Corneal transplantations were carried out using LEW rats as recipient and F344 rats as the donor. The recipient rats were randomly divided into 5 groups, receiving peribulbar SEB injection of a dosage of 30, 60, 90 or 120 microg/kg 7 days before and after operations. The negative control group received saline injection while the positive control group received glucocorticoid(GC), FK506, CsA or interleukin-1 receptor antagon ist (IL-1ra), respectively. The survival time and rejection index of corneal grafts within 30 days postoperation were examined and recorded using anti-rejection index method. The inflammatory cell infiltration of the recipient cornea and changes of local NK cells were examined by PE-conjugated anti-NK1.1 monoclonal antibody.
Results: The grafts in the group receiving injection of 120 microg/kg SEB survived 22 days longer than the negative control group. Their survival time is also significantly longer than the groups treated with FK506, CsA, GC or IL-1ra. The graft rejection index was 3.42+/-2.18 in the rats receiving 120 microg SEB/kg,but 6.58+/-3.15 in the negative control group (P<0.01). The edema and new blood vessel indexes were also significantly reduced. The immunostaining showed that the number of NK cells increased following injection of SEB.
Conclusion: Injection of SEB reduced the rejection to corneal transplants in rats, showing that the immune tolerance induced by superantigen SEB plays a role in the reaction at the immune privileged site.