Function studies of monocytes from patients with cyclic neutropenia.

In vitro studies of peripheral blood monocytes from patients with cyclic neutropenia have shown them to be able to phagocytize and kill bacteria as efficiently as PMN's, but not monocytes, from normal controls at both low and high ratios of bacteria to leukocytes. Monocytes from these patients, as well as from normal controls, are able to respond to chemotactic stimuli in vitro. In vivo Rebuck skin-window studies revealed the mononuclear cell response to be normal in these patients, even in the complete absence of circulating and inflammatory exudate neutrophils. These findings suggest that peripheral blood monocytes from patients with cyclic neutropenia are as phagocytically and bactericidally competent as normal peripheral blood neutrophils. As "stimulated" cells, they may serve as an effective line of defense against bacterial infections during periods of neutropenia in these patients.