HK cells protect against spontaneous apoptosis of B-CLL cells.
Freshly isolated B-CLL cells were cultured at 2 × 106 cells per milliliter alone; in coculture with a human, follicular, dendritic cell line (HK); or with an ovarian cell line (OVCAR3) at 1 × 105 cells per milliliter. The percentage of spontaneous apoptosis was measured by double staining with annexin V–FITC and PI, followed by flow cytometric analysis (mean ± SD). (A) B-CLL cells were cultured alone or in coculture with HK cells for 24, 48, 72, or 96 hours before measuring apoptosis (n = 9). (B) Numbers of viable cells were monitored in cultures of CLL B cells on the basis of 7-AAD exclusion assay (mean ± SD, n = 3). (C) Data are summarized for all 6 B-CLL specimens tested, with apoptosis measured at 24 hours. (D) CLL B cells were cocultured with either HK cells or OVCAR3 cells for 24 hours. Bars represent mean for each group (n = 6).
