Two-dimensional CL analysis of the cytokine dataset. Expression levels of individual cytokines are represented by shades of blue to red in the central heatmap, with highest values in dark red and the lowest in dark blue. In this unsupervised bicluster analysis, healthy subjects (indicated by yellow boxes directly below heatmap) clustered together in 2 discrete groups, sharply distinct from CLL patients (indicated by turquoise boxes). TTFT status of CLL patients is indicated by blue (≥ 5 years), black (< 5 years), or gray (unknown) coloring in bar above heatmap. CLL patients with short TTFT formed a discrete CL. Three distinct sets of correlated cytokines (CLs) are highlighted by black, green, and pink boxes on heatmap. All available data on the entire panel of cytokines were used for this analysis with the exception of CCL17, because CCL17 values were not available for all patients.