[The role of superantigen SEB-induced immunotolerance in the immune privileged site]

To investigate if the immunological tolerance induced by superantigen staphylococcus enterotoxin B (SEB) takes part in the reaction at the immune privileged site.

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.

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.

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.