Figure 1.

Effect of UVB radiation on the inhibition of IFN-γ-induced ICAM-1 mRNA and surface expression in DNA-repair-deficient versus normal cells. (a) RT-PCR on ICAM-1 (Left) and GAPDH (Right) mRNA expression in normal (N46), XP-D (XP16BR), and TTD (TTD1BEL) cells. Cells were left unstimulated (lane 1) or stimulated with rhIFN-γ (lanes 2–6). In lanes 1 and 2, cells were sham irradiated, in lanes 3–6, cells were exposed to decreasing doses of UVB radiation (lane 3, 100 J/m²; lane 4, 50 J/m²; lane 5, 25 J/m²; and lane 6, 12.5 J/m²). IFN-γ (500 units/ml) was added immediately after UVB radiation exposure and cells were harvested after a 4-h incubation period. Data are shown as fluorescence of ethidium bromide-stained gels and represent one of three essentially identical experiments. (b) Summary of RT-PCR results from three XPD (⋄), three normal (○), and three TTD (▵) cell strains. IFN-γ-induced ICAM-1 mRNA expression is given as percent of ICAM-1 mRNA expression in sham-irradiated, IFN-γ-stimulated cells and is plotted against UVB radiation (J/m²). Each curve represents mean values of three independent experiments. Standard deviation for each mean was less than ±15%. (c) Summary of FACS analysis results from three XPD (⋄), three normal (○), and three TTD (▵) cell strains. IFN-γ was added immediately after UVB radiation exposure and cells were harvested after a 24-h incubation period. IFN-γ-induced ICAM-1 surface expression is given as percent of ICAM-1 surface expression in sham-irradiated, IFN-γ-stimulated cells and plotted against UVB radiation (J/cm²). Each curve represents mean values of three independent experiments. Standard deviation for each mean was less than ±15%.