Relative expression of IL-6 mRNA. The relative expression levels of IL-6 mRNA compared with the reference calculated by the logarithm base 2 of ratio (Cy5/Cy3) at each time point were plotted. Expression of IL-6 mRNA in peripheral blood cells from 18 patients with RA was measured using a DNA microarray before and after administration of tocilizumab. Bars and error bars show means plus SEs.