Figure 4: Mechanism of MDSC in Cross-talk with Immune Cells and AID Suppression. (A) MDSC is thought to be a central player in regulating immunity via interplay with macrophages (MΦ), dendritic cells (DC), NK cells, regulatory T cells (Treg), effector T cells (Teff), etc. MDSC regulate immune cells via cell contact and soluble mediators. The interaction of MDSC with different immune cells is indicated with thin-line arrow (activation) and thickline inhibitory sign (inhibition). (B) M1/M2 polarization of MDSC may affect disease and health. M1 and M2 MDSC show pro-inflammatory and antiinflammatory (tolerogenic) activities dependently on the expression of their respective signature genes. Therefore, manipulation of MDSC polarization can used to treat diseases. In this context, M2-polarized MDSC can be used as a novel cell-based therapy for AID. However, whether M1-polarized MDSC aggravate this disease is not ascertained. Arrow (thin line) and inhibitory sign (thick line) indicate promotion and suppression, respectively.