Networks of highly correlated cytokines in sera of patients with mild and aggressive CLL. “Connectivity mosaics” representing matrices of correlation coefficients are shown for serum cytokines from patients with TTFT of ≥ 5 years (left) and patients with TTFT of < 5 years (right). Individual cytokines are identically listed on x- and y-axes with A, B, C, and D indicating selected groups of highly correlated cytokines. Color shades indicate the type of correlation, with red = positive, blue = negative, and green = absent correlation. Light white lines indicate the borders of defined CLs of interconnected cytokines. For clarity, we indicate the relationship between groups of highly correlated cytokines determined by mosaic analysis and the 3 cytokine CLs (CL1, CL2, and CL3) identified by unsupervised cluster analysis (indicated in gray at far left). Some areas in the mosaic plot which differ in correlation strength between the 2 TTFT cohorts are delineated by pink-striped edges. 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.