MPO and Iron deficiency anemia: As a result, iron deficiency could lead to decreased myeloperoxidase activity in neutrophils, impaired bactericidal activity, decreased T-lymphocyte numbers with thymic atrophy, defective T-lymphocyte-induced proliferative response, impaired natural killer cell activity, impaired lymphocytic interleukin-2 synthesis, and reduced production of macrophage migration inhibition factor [19].