Synergic Effects of Immunosuppressive Agents on T Lymphocyte Function and Cytokine Expression Pattern.

The regimen including mycophenolate mofetil (MMF) and cyclosporine A (CsA) has been successfully used as an effective method in the prophylaxis of acute graft versus host disease. Herewith we investigated the effect of CsA, mycophenolic acid (MPA) alone or in combination with anti B7–1 mAb on proliferation of T lymphocytes and their possible mechanisms. The T lymphocyte reaction system was established in vitro and was detected by 5-bromo-2-deoxyuridine incorporation method; the expression of IL-2, IFN-γ and IL-10 on mRNA and protein level were detected by RT-PCR and ELISA respectively. Experimental concentration of MPA (50μmol/L) and CsA(0.33μmol/L) inhibited the T lymphocyte proliferation significantly. CsA in combination with anti B7–1 mAb(10mg/L) had a much stronger effect on the inhibition(p<0.01). There was no difference between groups treated either with MPA or with the combination of MPA and anti B7–1 mAb. Both of CsA and MPA could inhibit the protein expression of IL-2 and IFN-γ. The protein expression of IL-2 were 99.70±9.15 pg/ml, 48.19±8.67pg/ml and 42.73±14.64 pg/ml in groups of control, treated with CsA or MPA respectively. The protein expression of IFN-γ in the group treated with CsA or MPA decreased significantly than the control (6.81±5.24 pg/ml, 7.87±4.22 pg/ml vs 82.42±25.55 pg/ml, p<0.05). Compared with that treated with CsA alone, The protein expression of IFN-γ in the group treated with CsA in combination with anti B7–1 mAb decreased significantly (0.30±0.52 pg/ml vs 6.81±5.24 pg/ml, p<0.05). Both of CsA and MPA increased the protein expression of IL-10. Compared with MPA alone, MPA in combination with anti B7–1 mAb increased significantly the expression of IL-10 (941.90±56.61 pg/ml vs 770.95±126.85 pg/ml, p<0.05). The relative expression level of IL-2 mRNA (IL-2/GAPDH) and IFN-γ mRNA (IFN-γ /GAPDH) in the CsA or MPA group was significantly lower than the control (p<0.01). The relative expression level of IFN-γ mRNA in combination group of CsA with anti B7–1 mAb decreased even more significantly (0.38±0.05 vs 0.59±0.02, p<0.01). On the other hand, this combination could up-regulate IL-10 mRNA expression (1.80±0.13 vs 1.38±0.06, p<0.01). Combination of MPA with anti-B7–1 mAb showed a statistically significant increase in IL-10 mRNA expression (1.28±0.06 vs 0.84±0.09, p<0.01) as compared with MPA alone. In conclusion, MPA and CsA induced the changes of cytokine expressive spectrum and the Th1 and Th2 shift might be involved in the immunosuppressive effect. The combination of immunosuppressive agents, especially with anti B7–1 mAb had a synergic effect.