In conclusion, our observations could demonstrate that different populations of peripheral T (CD4+, CD8+, and γδ) and B cells can differentially produce IFN-γ, IL-4 IL-10, and IL-17 according to the repertoire of IgG produced by each group of HTLV-1-infected individuals (AC, HAM, and ATLL), what may collaborate on framing the control or development of disease. This evidence concerns the gene IL4 and adult T-cell leukemia/lymphoma.