Figure 1

Growth curves and p19 Gag expression in HTLV-1 T-lymphocyte immortalization assays. Human PBMCs (2 × 10⁶) were cultured alone or with irradiated donor cells (SLB-1) in 24-well plates. Cell viability was measured weekly by trypan blue exclusion (0–13 weeks after co-cultivation) and growth curves are shown. PBMCs were infected with HTLV-1 in the presence of IL-2 (10 U/mL; supplemented from day 1 following HTLV-1 infection) or in the absence of IL-2. PBMCs with no stimulation, PBMCs stimulated with PHA and IL-2 irradiated SLB-1 cells served as controls. The results showed that only HTLV-1-infected cells continued to proliferate beyond 6 weeks in culture. Viable cell numbers were significantly different over time between treatment groups (p < 0.0001). While the PBMC+HTLV-1+IL-2 group cell numbers increased slightly over time, the remaining group cell numbers decreased over time, but the PBMC+HTLV-1 group cell numbers decreased only slightly. After using Dunnett's method to adjust for multiple comparisons, the HTLV-1-treated groups both had significantly higher cell numbers than the PBMC (control) group (p < 0.0001).