[Immune tolerance induced by staphylococcal enterotoxin B for the treatment of rat high-risk corneal transplantation rejection].

OBJECTIVE

To determine the mechanism of staphylococcal enterotoxin B (SEB) induced immune tolerance in the treatment of high-risk corneal transplantation in the rat.

METHODS

Fisher 344 rats were used as donors and Lewis rats were used as recipients. Corneal neovascularization was induced by sutures. The rats were divided randomly into five groups in a masked fashion. In the 4 SEB-treated groups, 0.2 ml SEB were intraperitoneally injected before the keratoplasty at concentrations of 25 microg/kg, 50 microg/kg, 75 microg/kg and 100 microg/kg, respectively. The control group received a saline buffer injection intraperitoneally. All allografts were observed and scored for 30 days. Meanwhile, the infiltration of lymphocytes in the allografts, the percentage of lymphocyte subpopulations in the immune organs, the proliferation ability of the lymphocytes and the cytokines in the serum were measured.

RESULTS

The SEB at the concentration of 25 microg/kg did not prolong the survival time of the allografts as compared to the control group. With the increase of the concentration of SEB, the survival time in the other three SEB-treated groups were prolonged significantly and the 75 microg/kg group showed the best results. The infiltration of the lymphocytes in the allografts and the percentages of CD4+ and CD8+ lymphocytes in the immune organs in the SEB treated groups were reduced. The proliferation ability of the lymphocytes in SEB treated groups was decreased; the concentration of IL-2 was lower while the concentration of IL-10 was higher in the serum in the SEB treated groups.

CONCLUSIONS

SEB at an optimal concentration is effective in inhibiting immune rejection in high-risk corneal transplantation. The mechanism of SEB induced immune tolerance is related to the reduction of the number and the immune tolerance status of the lymphocytes.