The Effect of Mesenchymal Stem Cells on the Expression of IDO and Qa2 Molecules in Dendritic Cells

Mesenchymal stem cells (MSCs) have been shown to reduce the activity of immune cells, including dendritic cells (DCs). But the exact mechanism of mesenchymal inhibition of DCs is still unknown. In this study, the effect of mesenchymal cells on the expression of indoleamine dioxygenase (IDO) and Qa2 molecules in DCs was evaluated. MSCs and DCs were respectively isolated from the bone marrow and spleen of BALB/c mice. Then DCs were co-cultured with MSCs in the present and absence of lipopolysaccharides (LPS). Then the expression of mRNA and protein of IDO and Qa2 molecules were investigated in DCs that were treated with MSCs. The expression of IDO and Qa2 mRNA in DCs that were treated with MSCs did not significantly differ from the control group. The expression of IDO protein in DCs that were cocultured with MSCs (in 1:10 and 1:50 ratios) in absence of LPS was increased, although they were not statistically significant (P values: 0.24 and 0.18, respectively). The expression of Qa2 protein in DCs that were co-cultured with MSCs (in 1:10 and 1:50 ratios) in presence of LPS was increased, although they were not statistically significant (P-values: 0.09 and 0.33, respectively). Our results denied the possibility that MSCs led to the induction of tolerogenic DCs by increasing the expression of the IDO and Qa2 immunomodulatory molecules.