Objective: To explore the effect of mycophenolic acid (MPA) on activation and proliferation of T lymphocytes in vitro.
Methods: Peripheral blood mononuclear cells (PBMNC) were prepared from normal donors, and incubated with phytohemagglutinin (PHA) with or without MPA and cyclosporin A (CSA) in vitro. After incubation, the expression of T lymphocytes activation markers such as CD(69), CD(25) and CD(3) on cell surface was assayed with flow cytometry. At the same time, incorporation rate of bromodeoxyuridine (BrdU), an analog of thymidine, was detected for T lymphocytes proliferation by flow cytometry.
Results: (1) Both MPA and CSA could significantly inhibit the expression of CD(3) on T lymphocyte surface. After 96 hours, the expression of CD(3) in MPA and CSA group was (37.60 +/- 7.89)% and (55.85 +/- 13.64)% respectively, while that of the control group was (74.20 +/- 7.51)%. (2) The expression of CD(3) was still significantly inhibited when MPA was added to PBMNC which was prior incubated with PHA for 72 hours. (3) MPA, CSA did not affect the expression of CD(69) on T lymphocyte surface after 24 hours. (4) Both MPA and CSA could significantly inhibit the expression of CD(25) on T lymphocyte surface. After 72 hours, the expression of CD(25) in MPA group and CSA group was (37.15 +/- 7.15)% and (62.47 +/- 12.50)% respectively, while that of the control group was (84.85 +/- 8.46)%. (5) MPA (10(-5) mol/L) significantly inhibited the incorporation of BrdU in PHA activated PBMNC (9.77 +/- 7.55)% VS (43.27 +/- 18.85)% in control (P = 0.046). Cell cycle analysis showed that MPA decreased especially the percentage of S phase cells, while the percentage of G(0)/G(1) phase cells was comparatively increased and that of G(2)/M phase cells was not changed.
Conclusions: The expression of CD(3) and CD(25) was inhibited by MPA. The expression of CD(3) could be suppressed by MPA even if MPA was added to PBMNC after PHA. It is suggested that MPA could suppress T lymphocyte activation and could also reverse T lymphocyte activation. MPA could suppress T lymphocyte proliferation by down-regulating the DNA synthesis. MPA decreased especially the percentage of S phase cells decreased and increased comparatively the percentage of G(0)/G(1) phase and G(2)/M phase cells.