Effect of iron therapy on phagocytosis and bactericidal activity in neutrophils of iron-deficient infants.

Phagocytosis and bactericidal capacity of neutrophils were measured in 10 iron-deficient infants age 6-23 mo. All infants had hemoglobins less than 11 mg/dL with low saturation of transferrin and serum ferritin but were otherwise in good health. Neutrophil function and iron status were assessed at 0, 3-5, 15, 30, and 90 days of oral iron therapy. Phagocytosis was unaffected in iron deficiency and remained unchanged during therapy. Bactericidal capacity was severely impaired prior to treatment. After 3-5 days of ferrous sulfate administration, there was no significant improvement. At day 15 it returned to normal ranges and remained so at days 30 and 90. The sequence of events suggests that iron does not have a direct effect upon circulating neutrophils but, rather, that it is required during the development of neutrophils in the bone marrow.