Inhibitory effects of HBZ-specific antibody on T cell activation of HAM/TSP patients. (A) Detection of immortalized memory B cells producing HBZ-specific antibodies in HAM/TSP patients. The immortalized B cells were generated from three HAM/TSP patients with anti-HBZ in serum, and production of HBZ-specific antibodies (closed bars) was detected using LIPS assay. (B) Detection of HBZ proteins using an anti-HBZ (+) B cell culture supernatant and rabbit anti-HBZ serum by western blot. The nuclear proteins were extracted from HTLV-1-uninfected (Jurkat and MOLT-3) and HTLV-I-infected (MT-2 and HUT102) cell lines and HBZ/pRen2-untransfected and transfected 293T cells. Detection of HBZ proteins was confirmed by western blot (i) representative image and (ii) the intensity of HBZ proteins. (C) Representative dot plots of CFSE staining in CD8+ T cells of a HAM/TSP patient with HBZ-specific antibody or control IgG after culture for 6 days. (D) Inhibitory effects of HBZ-specific antibody on spontaneous proliferation of CD8+ T cells (i) and CD4+ T cells (ii) in PBMCs of HAM/TSP patients after culture for 6 days by Wilcoxson matched-pairs signed rank test. The data were obtained from 7 HAM/TSP patients without anti-HBZ response (closed circles) and one ND (opened circle) as control. (E) Comparison of frequencies of CD4+CD25+ T cells (i) and CD8+CD25+ T cells (ii) of NDs, HAM/TSP patients with and without antibody responses for HBZ by Mann–Whitney test. The data were obtained from twelve NDs, and five and ten HAM/TSP patients with and without antibody responses for HBZ, respectively. The horizontal line represents the mean.