Neutrophils and zinc in infection-prone children with sickle cell disease

Abstract

Neutrophils can be distinguished as EA negative (EA-N) or EA positive (EA+N), according to rosette formation with sheep erythrocytes. EA- neutrophils show a bactericidal activity 50% to 70% lower than EA+ neutrophils. Thirty children with sickle cell disease were studied during steady state and crises/infections, together with matched control children. EA+ and EA- neutrophils, zinc levels in the body, and frequency of previous bacterial infection were evaluated. Sixty percent of the patients (18/30) had zinc deficiency (zinc less than 8.5 micrograms/10(10) RBC): of this group, more than three fourths (14/18) had a high frequency of infections (greater than or equal to 3/yr) and most of those (11/14) also had an increased percentage of EA- neutrophils (80% to 85% v 35% to 45% in control subjects). Only 4/18 of patients with zinc deficiency had a low frequency of infections, and only one of these four had a higher percentage of EA- neutrophils. In patients with normal zinc levels (12/30 or 40%), only three had frequent infections, but only one of these had an increased percentage of EA- neutrophils. The number of EA+ neutrophils increased after stimulation with epinephrine or during crises/infections. In six patients with more pronounced zinc deficiency and more severe crisis/infection, a delay in the increase of EA+ neutrophils occurred and was corrected by treatment. These findings suggest that a higher percentage of neutrophils with less bactericidal activity in many children with sickle cell disease and zinc deficiency may be a factor in the higher incidence of infections noted in these patients, and zinc might play a role in the formation, release, and activity of neutrophils.