Figure 2.

Lack of regulatory function in CD4⁺CD25⁺ T cells from HAM/TSP patients. A total of 1 × 10⁵ CD4⁺CD25^– T cells/well from HDs were labeled with CFSE. They were cultured for 6 days in the culture medium in the absence or presence of 2.5 μg/ml anti-CD3 antibody (top 2 panels). They were also cultured for 6 days in 2.5 μg/ml anti-CD3 antibody added to culture medium with 1 × 10⁵ irradiated allogeneic CD4⁺CD25⁺ T cells from HDs or with 1 × 10⁵ irradiated CD4⁺CD25⁺ T cells from HAM/TSP patients (bottom 2 panels). The data indicate that regulatory function in CD4⁺CD25⁺ T cells from HAM/TSP patients is reduced in comparison with that in CD4⁺CD25⁺ T cells from HDs. Failure of CD4⁺CD25⁺ T cells to suppress lymphoproliferation of activated HD cells was observed in separate experiments with cells from 4 HAM/TSP patients, while suppression of activated HD cell proliferation by allogeneic HD CD4⁺CD25⁺ T cells from 2 HDs was demonstrated.