Binding of CLL Abs to apoptotic cells, macrophages, and membrane vimentin expression on live CLL cells. (A) CLL mAbs bind apoptotic Jurkat T cells. Jurkat T cells were UV-light exposed (51 mJ/cm2) for apoptosis induction. After 18 hours, CLL mAbs were incubated for 45 minutes followed by FITC–anti-IgM or FITC–anti-IgG. Blue line indicates the CLL mAb binding to apoptotic cells in the absence of the competitor, and the red line is in the presence of the competitor, 100 μg/mL MDA-LDL. Black line indicates secondary Ab only, and filled gray curve indicates cells only. (B) I83 IgM reacts with vimentin expressed on surface membrane of human macrophages. Purified macrophages cultured in 20% human serum for 6 days followed by 2 days of serum deprivation and analysis in FACS. Red line indicates cells binding the mAb, and green line indicates cells with secondary Ab only. (C) I83 CLL cells show distinct surface membrane staining (arrow) with antivimentin V9 mouse mAb. Secondary Ab was anti–mouse IgG–Alexa594. Overlay image with differential interference contrast. The insert table shows data from immunofluorescence analysis of membrane vimentin on 14 different primary CLL cells.
