OBJECTIVETo investigate the toxicity of anti-CD25 monoclonal antibody (mAb) to rat cornea and its effects on the cytokines in the aqueous humour after penetrating keratoplasty (PKP), thereby evaluating the effect of anti-CD25 mAb in preventing corneal allograft rejection.

METHODSThe corneal toxicity of anti-CD25 mAb at 50, 100 and 200 microg administered via subconjunctival injection was evaluated in 12 SD rats by histological examination and transmission electron microscopy. Another 93 SD rats were randomized into 5 groups, and transplantation of corneal allograft from Wistar rats was performed in 4 groups with the other group as the normal control. The 4 allograft groups were treated with saline, 100 microg anti-CD25 mAb, 100 microg anti-CD25 mAb with 50 microg dexamethasone, and 50 microg dexamethasone, respectively. The graft rejection was observed, the aqueous humour levels of IFN-gamma and IL-4 were measured with ELISA, and IFN-gamma mRNA expressions in the grafts detected with RT-PCR.

RESULTSanti-CD25 mAb at 50 or 100 microg did not show significant toxicity on the cornea, but at 200 microg, the mAb caused swelling of the corneal stromal cells and endothelial cells. After corneal allograft transplantation, a significant delay in allograft rejection was observed in the 3 groups with mAb or dexamethasone treatment as compared with that in saline group (P<0.05). IFN-gamma mRNA expression in the allograft on days 11 after PKP and in the aqueous humour on days 6 and 11 was markedly increased in saline group compared with that in the 3 treatment groups (P<0.05). The mean IL-4 level in the aqueous humour was significantly higher in the mAb group than in saline group (P<0.05), but markedly lower in anti-CD25 mAb+dexamethasone and dexamethasone groups than in anti-CD25 mAb group (P<0.05).

CONCLUSIONSAnti-CD25 mAb at 20 and 100 microg does not obviously affect the rat corneas. Anti-CD25 mAb inhibits IFN-gamma expression and promotes IL-4 the expression to reduce corneal allograft rejection, whereas anti-CD25 mAb with low-dose dexamethasone inhibits both IFN-gamma and IL-4 expressions to more effectively promote the graft survival.