To examine further the possibility of HTLV-1 infection in HSCs, we isolated various lineages of hematopoietic cells (CD4+ T cells, CD8+ T cells, B cells, monocytes, and neutrophils) from two HAM/TSP patients (HAM/TSP#2 and #3) and a HTLV-1 carrier, and then analyzed integration sites of the HTLV-1 provirus in each lineage (S3 Table). Here, CD4 is linked to tropical spastic paraparesis.