Hyperproliferation of CD3⁺ T cells in HTLV-1/HU-NSG mice. Representative histologic analysis of the spleen of HTLV-1/HU-NSG mice and mock HU-NSG mice killed 14 weeks after reconstitution. (A-B) Immunohistochemical analysis of human CD3 expression in the spleen of HTLV-1-HU-NSG mice in comparison with mock-infected HU-NSG mice (×40 magnification). (C) Quantification of hyperproliferation of CD3⁺ T cells in the BM, thymus, spleen, and MLN of HTLV-1-HU-NSG mice in comparison with mock mice reconstituted with the same donor CD34⁺ cell preparation (HTLV-1, n = 6; mock, n = 4).