Survival of CLL B cells and outgrowth of NLC in vitro.

(A) Marrow stromal cells protect CLL B cells from spontaneous apoptosis in vitro. Presented is the mean relative viability (±SEM) of CLL B cells from 6 patients cultured in the presence (boxes) or absence (diamonds) of the murine marrow stromal cell line M2-10B4. The viability of the CLL cells was determined at the time points indicated. This is displayed as the normalized percentage viability relative to that noted at the initiation of the culture (day 0). (B) Outgrowth of adherent NLC from PBMC of patients with CLL. Cultures of PBMC from 4 representative patients with CLL were examined microscopically for the number of adherent cells at the indicated time points. Lines connect the mean number (±SEM) of adherent cells from each patient counted at 200× magnification in 3 different visual fields at each time point.