Bright VEGF Expression is Identified in CLL Cells by Flow Cytometry. 21 cases were examined by flow cytometry for VEGF expression. The panel on the left is a plot of VEGF vs CD19 expression in a control case. The level of VEGF expression by the CD19+ B cells in the control cases was equal to that of the CD19- T cells. A plot of VEGF vs CD19 in one of the CLL cases is illustrated in the right panel. The CD19+ CLL Cells were 1.4–2.0× Brighter than the CD19-CD5+ T cells in the same samples. VEGFR-2 (KDR, Flk-1): In most cases, only scattered cells in the infiltrates were positive, with the exception of two cases, one of which is illustrated, in which the vast majority of lymphocytes were positive. The microvessel density of these two cases did not markedly differ from the other cases in this group.