To investigate the regulatory effect of activated Treg cells on the migration of NKT cells in mice.

Treg cells and NKT cells were isolated and purified, then Treg cells were modified by the lentivirus carrying Foxp3 and the activation of Treg cells were verified. The activated Treg cells and NKT cells were co-cultured in vitro and flow cytometry was used to detect the number of NKT cells. The secretion of intracellular factors (IL-4 and IFN-γ) in the NKT cells was measured with reverse transcription polymerase chain reaction (RT-PCR) and enzyme-labeled immunosorbent assay (ELISA). Ovalbumin (OVA)-induced asthma mouse models were established and used to observe the effect of Treg cells modified by Foxp3 on the migration of NKT cells in vivo.

The expression of Foxp3 was significantly up-regulated in the Treg cells modified by Foxp3 (Le-Foxp3 group). CFSE assay showed that the Treg cells carrying Foxp3 significantly inhibited the proliferation of autologous CD4⁺ CD25^- T cells (Teff cells), and ELISA showed that the levels of IL-10 and TGF-β were increased markedly in the Le-Foxp3 group compared with the control group (the cells were infected with the lentivirus carrying scrambled sequence, Le-scr group). After co-culture of the Treg cells and NKT cells in a transwell culture plate, the flow cytometer showed that the NKT cells in the lower chamber were (221.15±79.36) in the Le-Foxp3 group and (649.38±153.97) in the Le-scr group. Meanwhile, the levels of IL-4 and IFN-γdecreased remarkably. The results from OVA-induced asthma model showed that the forced expression of Foxp3 remarkably increased the NKT cells in the spleen and the peripheral blood, while decreased the NKT cells in the lungs.

Infection of lentivirus carrying Foxp3 can activate Treg cells. The activated Treg cells can inhibit the activation and migration of NKT cells in vitro and affect the distribution of NKT cells in OVA-induced asthma mouse model.