Figure 3. Survival of CD34⁺ cells from MF patients is increased by IL-1β and TNF-α.

(A) CD34⁺ cells from MF patients (n = 20) or CB (n = 8) were in vitro treated for 4 days with factors alone and the percentage of cell viability was assessed after Annexin V/PI staining, as described in Methods. At variance with CB-derived cells, TNF-α and IL-1β alone significantly stimulated the survival of MF-derived CD34⁺ cells as compared with untreated cells and the CB-derived counterparts. Conversely, ATP and TIMP-1 were ineffective in normal and diseased cells.(B) In selected experiments, before Annexin V/PI staining, MF- (n = 10) and CB- (n = 6) derived CD34⁺ cells were also labeled with a MoAb against the human CD38 antigen and the CD34⁺ CD38⁻ cells were gated and cell viability was analyzed. Once again, multiple combinations of cytokines with IL-1β or TNF-α significantly stimulated the survival of MF- and CB-derived CD34⁺ CD38⁻ cells. Notably, this was not true for ATP+ TNF-α+ TIMP-1. No differences were observed between MF patients and CB. All data are presented as mean ± SEM. (**p ≤ 0.01; ***p ≤ 0.001; ****p ≤ 0.0001 vs untreated cells (CTR)) (^#p ≤ 0.05; ^##p ≤ 0.01 vs CB).