Expression and purification of the mGITR-Fc fusion protein and its effect on CD4⁺ T cells and dendritic cells in vitro.

Glucocorticoid‑induced tumor necrosis factor receptor related protein (GITR) is a member of the tumor necrosis factor receptor superfamily. The present study attempted to obtain the mouse GITR‑Fc fusion protein and investigate its function on the proliferation of CD4+ T cells and on the expression of mGITR ligand (mGITRL) on dendritic cells. The sequences of the mouse (m)GITR gene and mouse immunoglobulin G Fc (mIgGFc) were amplified from mouse spleen cells and introduced into a pET‑32a(+) vector. Following the induction, purification and validation of the mGITR‑Fc fusion protein, the mGITR‑Fc fusion protein was used to analyze its function on the proliferation of CD4+ T cells and on the expression of mGITR on dendritic cells. A recombinant plasmid containing the mGITR gene fragment and mIgGFc was constructed, and the recombinant mGITR‑Fc fusion protein was successfully expressed. The exogenous mGITR‑Fc fusion protein inhibited the proliferation of CD4+ T cells, dependent on the presence of mGITRL. The exogenous mGITR‑Fc fusion protein also inhibited the expression of mGITRL on the dendritic cells. In conclusion, the mGITR‑Fc fusion protein was confirmed to exhibit biological functions of a co‑stimulatory signal and reverse signal. These experiments provide the basis for further investigation of the function of the mGITR‑Fc fusion protein on certain autoimmune diseases.