CD4 and Tangier disease: Interestingly, immune system abnormalities that have been described in conditions characterized by iron overload as hemochromatosis include decreased phagocytosis by the monocyte–macrophage system; alterations in T-lymphocyte subsets, with an enhancement of CD8 and suppression of CD4; impairment of immunoglobulin secretion; and suppression of complement system function [24,25,26].