Monocyte functional capacity in chronic neutropenia

The bactericidal activity of monocytes from a child with chronic benign granulocytopenia who has had virtual absence of neutrophils yet minimal infections since birth was examined against Escherichia coli and Staphylococcus aureus and compared with that of monocyte and neutrophils from 20 control subjects. Studies on monocyte function in this patient with no neutrophils revealed normal monocyte kill of both organisms when compared with control monocytes. Monocyte and neutrophil killing of both organisms was similar in control subjects at bacteria to phagocyte ratios of 1:1. When ratios of 3:1 were employed, however, control neutrophils were more effective than control and patient monocytes in reducing the number of viable organisms. These findings support the neutrophil as the more effective blood phagocyte but stress the importance of monocyte functional capacity in patients compromised by granulocytopenia or neutrophil functional defects.