Reduced phagocytic activity mediated by C3b and Fc monocyte receptors from children with sickle-cell disease

The causes of high morbidity due to infection among children with sickle-cell disease (SD) are unknown. Immunological studies have focused on spleen function, on the alternative complement pathway, and recently on phagocytic activity. We evaluated Fc receptor-mediated phagocytosis (sheep red cells opsonized with rabbit anti-E IgG, EA) and C3b receptor-mediated phagocytosis (zymosan particles incubated with fresh serum) in 27 children with SD. The control group consisted of 28 normal children matched by age and sex. The phagocytic indices obtained for cells from patients with SD were significantly lower than those for the controls (P less than 0.001), both when EA and zymosan were used and independent of whether the zymosan particles were incubated with patient serum or with a pool of normal sera. The results suggest the absence of abnormalities in the alternative complement pathway but do indicate an intrinsic cellular defect.