Figure 4.

Loss of regulatory function in HTLV-I tax–transfected HD CD4⁺CD25⁺ T cells. CD4⁺CD25⁺ or CD4⁺CD25^– T cells from uninfected HDs were stimulated with 2.5 μg/ml anti-CD3 antibody and irradiated PBMCs and cultured for 4 days (HD CD25⁺ and HD CD25^–). Furthermore, to compare the suppressive activity of HD CD4⁺CD25⁺ T cells before and after HTLV-I tax gene transfection, CD4⁺CD25^– T cells from HDs were stimulated with 2.5 μg/ml anti-CD3 antibody and irradiated PBMCs and cultured for 4 days in the presence of equal numbers of HD CD4⁺CD25⁺ T cells or HTLV-I tax–transfected HD CD4⁺CD25⁺ T cells (Tax⁺ HD CD25⁺). After culture, [³H]thymidine was added for additional 16 hours. The suppressive activity of CD4⁺CD25⁺ T cells from HDs was inhibited by transfection with the HTLV-I tax gene. Data represent the mean of experiments with cells from 3 HDs.