Correlation between HTLV-1 proviral load and DC differentiation. Cells were incubated with IL-4 plus GM-CSF (50 ng/mL) for 5 days at 37°C in a 5% CO₂ atmosphere. After this period, CD14 and CD1a expression was analyzed by flow cytometry. HTLV-1 proviral load was performed by real-time polymerase chain reaction and was calculated as follows: number of copies per 100 cells = [Tax copies (β-globin copies/2)] × 100. (A-B) Linear regression analysis was used to test the correlation between HTLV-1 proviral DNA load (measured in PBMCs; x-axis) and the percentage of CD14⁺ cells (A) or CD1a⁺ cells (B; y-axis). Cells were obtained from HTLV-1–infected patients and purified with a MoFlo sorter configured for high-speed sorting. (C-D) Representative gels of HTLV-1 Tax sequence in fresh monocytes and monocytes cultivated with or without IL-4 plus GM-CSF for 5 days. (C) First-round polymerase chain reaction with DNA extracted from 1 donor (patient 21084; lanes 2-5). Second-round polymerase chain reaction with DNA extracted from the same donor (lanes 8-11). L indicates ladder, 50 bp. Lanes 5 and 11 are CD4⁺ cells obtained from day 0, fresh sample; lanes 4 and 10, monocytes obtained from day 0, fresh sample; lanes 2 and 8, monocytes isolated after 5 days in culture; lanes 3 and 9, monocytes isolated after 5 days in culture with IL-4 and GM-CSF; and lane 6, negative control (H₂O). (D) Polymerase chain reaction with DNA extracted from 1 donor (patient 23856; lanes 14-16). L indicates ladder, 50 bp. Lane 14 represents monocytes obtained from day 0, fresh sample; lane 15, monocytes isolated after 5 days in culture; and lane 16, monocytes isolated after 5 days in culture with IL-4 and GM-CSF. As a control, the β-globin gene was also investigated (below samples in panels C and D).