DFO does not increase the yield of HH Vδ2⁺ T cells, and HD Vδ2⁺ cells proliferate vigorously when added to allogeneic TCRαβ-depleted HH PBMCs. (A) 100 μM DFO completely blocks proliferation of Vδ2⁺ T cells in ZOL-stimulated HD PBMCs (n = 7). (B) Dose titration of DFO to identify a physiological window for T-cell proliferation (n = 1). (C) DFO does not improve the proliferation and yield of Vδ2⁺ T cells from patients with HH in ZOL-stimulated cultures (n = 3). Compared with ZOL-stimulated PBMCs from HD (n = 2), Vδ2⁺ T-cell proliferation from individuals with HH (n = 3) is negatively and dose dependently affected at even lower concentrations of DFO than their counterparts from healthy individuals. (D) HH Vδ2⁺ T cells (n = 3) proliferate when stimulated with ZOL in irradiated PBMCs from HDs, but the increase in number is significantly less than that found in HD Vδ2⁺ T cells (n = 3), which reveal normal, strong proliferation when stimulated in irradiated PBMCs from patients with HH. Overlay: Superimposed CTV histogram for HD Vδ2⁺ T cells responding in HH PBMCs (blue) vs HH Vδ2⁺ T cells responding in autologous PBMCs (red). ∗∗∗∗P < .0001; ns, not significant.