Effects of citropten, bergamottin and bergapten on IL-8 mRNA accumulation: semi-quantitative RT-PCR analysis. IB3-1 were treated with TNF-α in the presence of IC25 (a) or IC50 (b) concentrations of citropten, bergapten and bergamottin as indicated for 24 hours, RNA was extracted and RT-PCR performed with primers specific for IL-8 and β-actin RNA sequences. (-): untreated IB3-1 cells; (+): IB3-1 cells treated with TNF-α. Results represent the average ± S.D. of three independent experiments. For each experiment triplicate RT-PCR determinations were performed. (*) p < 0.05.