BACKGROUND:J2 takes functional domain (MHC CD4-D1/) of complex conjugate of CD4 molecule and MHC class II molecule as a target, and is a smal molecule compound obtained by computer screening from a chemical data containing hundreds of thousands of organic compounds. In the previous study, J2 was used in mouse models of skin transplantation and keratoplasty by oral and intraperitoneal injection. Results verified that J2 could prolong the survival time of grafts, and suppress occurrence of rejection. To better play the role of a drug targeting and to reduce systemic toxicity, J2 wil be further utilized in local treatment of keratoplasty rejection. OBJECTIVE:To investigate the inhibitory effect of new immunosuppressive agent J2 on CD4+ and CD8+T cel immune functions in rat models receiving alogenic penetrating keratoplasty. METHODS:Alogeneic penetrating keratoplasty model was established using the adult female Wistar rats as donors and Sprague-Dawley rats as recipients. Group A: normal Sprague-Dawley rats were injected with 0.05 mL placebo subconjunctivaly. Surgery rats were randomly divided into three groups. Group B: alograft rats were injected with 0.05 mL placebo subconjunctivaly after autologous keratoplasty. Group C: alograft rats were injected with 0.05 mL placebo subconjunctivaly. Group D: alograft rats were injected with 1% J2-nanosuspension 0.05 mL subconjunctivaly. The distribution of T cel subsets in peripheral blood was detected using flow cytometry at 3 days, 1, 2 and 3 weeks after transplantation and compared among groups. RESULTS AND CONCLUSION: There was no significant difference in total CD3+ T cels, CD4+ T cels, CD8+ T cels and CD4+/CD8+ in peripheral blood lymphocytes in group B at various time points. At 3 days and 1 week after surgery in group C, no significant difference in total CD3+ T cels, CD4+ T cels and CD8+ T cels was detected. At 1 and 2 weeks, the number of total CD3+ T cels, CD4+ T cels and CD8+ T cels increased, showing significant differences (P < 0.05). In group D, no significant hyperplasy was found in CD4+ T cels and CD8+ T cels at 1 and 2 weeks. The horizontal comparison of the same time point: the total CD3+ T lymphocytes of group D was significantly less than group C at 3 days, 1 and 2 weeks after operation (P < 0.05), whereas there was no significant difference at 3 weeks between the group D and group C. The number of CD4+ T lymphocytes in group D was less than in group C at 3 days and 1 week, but with no significant difference. The ratio of CD4+/CD8+ had no significant difference in group D compared with group C at 3 days, 1 and 3 weeks. J2 inhibits T lymphocyte proliferation and then inhibits T cel-mediated corneal alograft rejection.