Immunophenotypic analysis of murine MSCs and immune effects in mice. As detailed in “Materials and methods,” flow cytometry analysis was conducted to determine expression of MHC class I, MHC class II, CD80, and CD86 on cultured murine polyclonal null MSCs (A) and clonal Epo⁺ MSCs (B), prior to and following in vitro exposure to IFNγ. The dashed line represents the isotype control, the solid line represents the specific antibody, and the bolder line represents the specific antibody after IFNγ. As described in “Materials and methods,” polyclonal null C57Bl/6 MSCs (black dot) were implanted in Balb/c (white dot) recipients; splenocytes were recovered 15 days later and incubated in vitro for 24 hours with C57Bl/6 (▪) or Balb/c (□) MSCs; and supernatants were assayed for mouse IFNγ by ELISA (n = 5 per group) (C). Likewise, clonal Epo⁺ C57Bl/6 MSCs (black dot) were implanted in Balb/c (white dot) recipients; splenocytes were recovered 15 days later and incubated in vitro for 24 hours with C57Bl/6 (▪) or Balb/c (□) MSCs; and supernatants were assayed for mouse IFNγ by ELISA (n = 5 per group) (D).