Mesenchymal stromal stem cells (MSCs) are an attractive therapeutic model for regenerative medicine due to their pluripotency. MSCs are used as a treatment for several inflammatory diseases, including hepatitis. However, the detailed immunopathological impact of MSC treatment on liver disease, particularly for adipose tissue derived stromal stem cells (ADSCs), has not been described. Here, we investigated the immuno-modulatory effect of ADSCs on hepatitis using an acute ConA C57BL/6 murine hepatitis model. i.v. administration of ADSCs simultaneously or 3 h post injection prevented and treated ConA-induced hepatitis. Immunohistochemical analysis revealed higher numbers of CD11b+, Gr-1+, and F4/80+ cells in the liver of ConA-induced hepatitis mice was ameliorated after the administration of ADSCs. Hepatic expression of genes affected by ADSC administration indicated tissue regeneration-related biological processes, affecting myeloid-lineage immune-mediating Gr-1+ and CD11b+ cells. Pathway analysis of the genes expressed in ADSC-treated hepatic inflammatory cells revealed the possible involvement of T cells and macrophages. TNF-α and IFN-γ expression was downregulated in hepatic CD4+ T cells isolated from hepatitis livers co-cultured with ADSCs. Thus, the immunosuppressive effect of ADSCs in a C57BL/6 murine ConA hepatitis model was dependent primarily on the suppression of myeloid-lineage cells and, in part, of CD4+ T cells.