Induction of HLA class I and class II expression by IFN in adherent cells. (a) One example of basal and IFN-γ-induced expression of HLA-A, HLA-B, HLA-C (left) and HLA-DR (right) molecules on mesenchymal stem cells from bone marrow (BM) by fluorescence-activated cell sorting analysis. (b) Expression of HLA-A, HLA-B, HLA-C (left) and HLA-DR (right) molecules by BM-derived cells (n = 5; two normal, two osteoarthritis and one rheumatoid arthritis) and synovium-derived cells (n = 7; three rheumatoid arthritis, two normal, two osteoarthritis) after induction with 1,000 U/ml IFN-α, IFN-β and IFN-γ, shown as the fold increase of the mean fluorescence intensity over the control ± standard error of the mean. (c) Detection of the 6–16 early response gene to IFN, assessed by quantitative RT-PCR, normalized to GAPDH mRNA (n = 3 for synovium-derived and n = 4 for BM-derived cell samples). Results display the fold increase of the 6–16 gene in IFN-induced samples over nontreated samples. * P < 0.05.