Figure 1

Diagrammatic summary of the major CD4⁺ and CD8⁺ T-cell effector subtypes (as derived from naïve CD4⁺ and CD8⁺ T cells), the reported effects of mesenchymal stem cells (MSCs) on these effectors, and some clinically important disease associations for each. Bidirectional arrows indicate reported inter-conversion (plasticity) between Th1/Th17 phenotypes and Th17/iT_reg phenotypes that may be of relevance to MSC immune modulatory effects. Relevant references are indicated numerically for individual statements. CTL, cytotoxic T lymphocyte; DC, dendritic cell; DTH, delayed-type hypersensitivity; FOXP3, forkhead box P3 transcription factor; GvHD, graft-versus-host disease; IFN-γ, interferon-gamma; IL, interleukin; iT_reg, induced regulatory T cell; nT_reg, natural regulatory T cell; Th1, T helper type 1 cell; Th2, T helper type 2 cell; Th17, T helper type 17 cell; T_reg, regulatory T cell.