DC-HIL binds SD-4⁺ CTCL cells through distinct HS moieties. (A) All 3 CTCL lines, 2 non-CTCL lines, or normal CD4⁺ T cells (in vitro–activated) were incubated with control Ig (shaded histogram) or DC-HIL-Fc (open histograms) and stained with PE-conjugated anti–mouse IgG. Binding of DC-HIL was assayed by flow cytometry. (B) HuT-78 cells were left untreated (None) or treated with heparinase before incubation with DC-HIL-Fc. Binding of DC-HIL was assayed as before. (C) The 3 CTCL lines or normal activated CD4⁺ T cells were stained with 3 different anti–HS (F58-10E4, HepSS-1, and F69-3G10) mAb (open histogram) or control Ig, as a mixture of IgM plus IgG (shaded histogram). Expression of each epitope was assessed by flow cytometry. (D) MJ cells were pretreated separately with the 3 anti–HS mAb or control IgG (10 or 40 μg/mL) before DC-HIL binding assay. Data shown is MFI of DC-HIL-bound cells.