Parameters and T-cell subset compositions in the T-cell compartment of HDs, and individuals with and without HH with chronic iron overload; iron transport molecules are differentially expressed by T-cell subsets. (A) Healthy individuals (n = 30) have significantly less CD4⁺ and more CD8⁺ T cells than patients with chronic iron overload (compound n = 11, C282Y n = 22). (B) γδ T-cell absolute number is not significantly different in HFE (n = 33) and HD (n = 30). (C) Patients with HH (n = 33) have significantly more Vδ2^– T cells (Vδ2^–) than HD (n = 30) and highly significantly fewer Vδ2⁺ T cells. (D) Vδ2⁺/Vδ2^– ratio is inverted in patients with HH. (E) Expression of molecules involved in Fe import (ZIP8, ZIP1, DMT1) and Fe export (ferroportin) revealed for different T-cell subsets (n = 3 for Vδ1 and Vδ2; n = 5 for CD4⁺ and CD8⁺). ∗P < .05; ∗∗∗∗P < .0001; DMT1, divalent metal transporter 1; GAPDH, glyceraldehyde-3-phosphate dehydrogenase; ns, not significant; ZIP, zinc transporter.