The Th1 phenotype is dominant among HTLV-1 Env- and Tax-specific CD4⁺ T cells in patients with HAM/TSP.

This shows frequencies of IFN-γ and IL-4 SFCs/10⁵CD4⁺ T cells by parallel Elispot assays in 5 patients with HAM/TSP, 4 asymptomatic carriers (AC), and 3 uninfected controls (Un). Statistical analyses was performed within groups using the paired Student t test. Group A: 2-tailed P = .0222 (asterisk indicates significant), IL-4 responses ranged from 0% (undetectable) to 0.14% of CD4⁺ T cells (median, 0.014%), IFN-γ responses ranged from 0.12% to 0.44% (median, 0.36%). Group B: 2-tailed P = .8930 (not significant), IL-4 responses ranged from 0% to 0.17% (median, 0%), IFN-γ responses ranged from 0% to 0.11% (median, .045%). Group C: 2-tailedP = .0912 (not significant), IL-4 responses were undetectable, IFN-γ responses ranged from 0.021% to 0.066% (median, 0.035%).