Inhibitory effects of cytotoxin IL-2-PE40 on corneal allograft rejection

Abstract

Objective To examine the inhibitory effect of IL-2-PE40 on the mouse corneal allograft rejection. Methods A mouse corneal graft model was set up by using C57BL/6 mice as donors and Balb/c mice as recipients. In the treatment group, IL-2-PE40 (0.6 μg/g body weight) was intraperitoneally injected from the day of surgery every 12 h until rejection happened. In the control group, the equal volume of PS was injected intraperitoneally at the corresponding time points. The transplanted cornea was observed under slit-lamp twice a week and the transplanted corneal opacity and neovascularization were rated according to Horis grading standards. It led to the determination of rejection response. The survival of transplanted cornea was regarded to be stopped when the rejection occurred. The operated eyes were observed historically on the 10th, 15th, 25th and 35th day after the surgery, and the peripheral blood was collected for measurement of T cell subgroups and T lymphocyte colonies. Results The survival time of cornea in the treatment and control groups was (30.2±2.9) days and (15.1±2.1) days respectively. In the control group, rejection occurred on the 15th day after the surgery, CD4~+ cells started rise right after the surgery and increased most obviously on the 15th day [(63.9±4.0)%] and decreased afterwards. CD4~+ cells in the treatment group were increased slightly [(42.6±4.0)%] on the 15th day. The number of CD4~+ cells in the treatment group was obviously less than in the control group (P<0.01). No significant changes in CD8~+ cells were observed in both groups. The number of T lymphocyte colonies in the control group was increased at the beginning and dropped then. No obvious change was found in the treatment group. The number of T lymphocyte colonies in the treatment group was significantly less than in the control group (P＜0.01). Conclusion IL-2-PE40 is a highly specific immunosuppressive agent. It can delay the development of corneal graft rejection and reduce the percentage of T-helper cells significantly. It also works to weaken the forming capacity of the peripheral T lymphocyte colonies. Key words: Corneal transplantation; immunotoxins; Graft rejection; Mice