Total cell preparations enzymatically purified from dental pulp possess the generic mesenchymal stem cell phenotype. Human dental pulp stem cells have an inhibitory effect on alloantigen-evoked peripheral blood mononuclear cell proliferation and immunoglobulin (Ig) M and IgG production. hDPSCs inhibit allogeneic adaptive hyperimmune responses by their release of transforming growth factor beta as a result of allogeneic stimulation of T lymphocytes and the production of interferon gamma.