[Effect of rapamycin in inducing naïve murine effector T cell convert to regulatory T cell].

Objective: To study the effect of rapamycin in inducing naïve murine effector T cell (Teff) convert to regulatory T cell (Treg) in vitro.

Methods: The forkhead box protein 3 (FoxP3) negative Teff were isolated and purified from the spleen and lymph node of C57 BL/6 murines aged 6-8 weeks, then Teff were cultured in three groups with mature dendritic cells (mDC), B cells, and plate coated Anti-CD3. In addition, the control wells and the test wells were prepared in each group, rapamycin were not added in the control wells but added in the test wells with concentrations of 1, 10, 50, and 100 nmol/L. Percentages of FoxP3 positive Treg were examined by flow cytometry after 4 days in Anti-CD3 group and after 6 days in the other two groups.

Results: As shown by the flow cytometry, the percentages of FoxP3 positive Treg were as follows in three group: in the mDC group, it was 0.01% in the control well and 0.39%, 0.47%, 0.34%, and 0.26% in test wells; in B cell group, it was 0.01% in the control wells and 5.56%, 5.89%, 7.15%, and 4.72% in the test wells; in Anti-CD3 group, it was 0.93% in the control wells and 1.35%, 1.07%, 1.02%, and 1.19% in test wells. No significant difference was found between the test wells and control wells in the mDC group and Anti-CD3 group; however, the percentages of FoxP3 positive Treg was significantly different between the test wells and control wells in the B cell group (P < 0.01).

Conclusion: When B cell is acted as the antigen-presenting cell, rapamycin can effectively induce Teff convert to Treg in vitro.