Tumor proliferation in the LN correlates with disease progression. (A) Magnification (×200) of LN biopsies of 2 representative CLL samples: top panel, preferential Ki67 staining in proliferation centers; bottom panel, diffuse Ki67 positivity. (B) Ki67 expression was assessed by flow cytometry in CD3⁻ cells from the indicated anatomical sites. Shown are 2 representative patients of a total of 6 analyzed. Cutoffs in each sample were chosen so that PB cells were around 1% Ki67⁺ cells. (C) Ki67 expression in CD3⁻ cells from the indicated anatomic sites. Statistical comparison was by paired Student t test. (D) Kaplan-Meier analysis of time to treatment in all patients with LN biopsies (n = 17) based on E2F scores: dashed line, scores above the median; solid line, scores below the median.