Figure 2
Effects of preanalytical sample processing on urine chemokine assessment. (a) Sample preparation study. Correlation plots illustrating relationships between uCXCL9 (left panel) and uCXCL10 (right panel) measurement from 25 pairs of urine samples, prepared and stored with or without protease inhibitors. P-value and r from a Spearman correlation test. (b, c). Sample storage study. Changes in urinary chemokine concentration over various processing delay (24H, 48H and 72H) and at 4 °C (Panel b) or room temperature (Panel c) storage conditions. Raw data from 5 individual samples are presented as solid lines for CXCL9 (navy blue dots) and for CXCL10 (green triangles). The percentage change was calculated at each timepoint in comparison to reference sample, and mean percentage change at each timepoint is presented by dashed lines (navy blue for CXCL9 and green for CXCL10). RM-ANOVA was performed to assess intra-patient variability. CV was calculated between all 4 urinary chemokine levels and mean CV is given as the mean of all intra-patient CVs. Baseline refers to standard sample processing (within 3H after collection) and storage (freezing at − 80 °C).
