Effects of IFNγ on the DNA synthesis and gene expression. Upper panel: DSL-6A/C1 cells and PSC were either cultured alone (columns 1, 2, 5 and 6) or together (columns 3, 4, 7 and 8) in transwell plates. After IFNγ treatment for 48 h under serum-free conditions as indicated, proliferation of DSL-6A/C1 cells (columns 1-4) and PSC (columns 5-8) was assessed with the BrdU incorporation assay. One hundred percent cell proliferation corresponds to DSL-6A/C1 cells or PSC cultured alone and without IFNγ. Data from 12 separate cultures were used to calculate mean values and SEM. * p < 0.05 vs. untreated monocultures, # p < 0.05 versus untreated cocultures (Wilcoxon's rank sum test). Middle panel: DSL-6A/C1 cells were cultured with or without FCS and IFNγ as indicated for 24 h, before DNA synthesis was assessed with the BrdU incorporation assay. One hundred percent BrdU incorporation corresponds to controls cultured without IFNγ. Data are presented as mean ± SEM (n = 6 separate cultures); * p < 0.05 vs. control cultures (Wilcoxon's rank sum test). Lower panel: Monocultures of PSC and cocultures of PSC with DSL-6A/C1 cells were treated with IFNγ at 100 ng/ml for 24 h. The mRNA expression of CTGF, TGF-β1, IL-6, IL-1β and the housekeeping gene HPRT in PSC was analyzed by real-time PCR, and relative amounts of target mRNA were calculated as described in the "Methods" section. One hundred percent mRNA expression of each gene (dotted line) corresponds to PSC monocultures grown without IFNγ. Data of 3 independent experiments (with triplicate samples) were used to calculate mean values and SEM.