Impaired microbicidal capacity of mononuclear phagocytes from patients with type I Gaucher disease: partial correction by enzyme replacement therapy

The higher susceptibility to serious bacterial infections in patients with Gaucher disease (GD) may be due in part to defective function of phagocytic cells. We studied five patients with GD (type I) and examined the ability of granulocytes and mononuclear phagocytes from these patients to phagocytose and kill Staphylococcus aureus and to generate superoxide anion (O2-) on stimulation with fully opsonized bacteria. Serum-opsonized staphylococci were ingested equally by phagocytic cells from patients and controls. In the presence of normal serum, the extent of killing of S aureus and the release of O2- by granulocytes over incubation periods of 60 minutes and 30 minutes, respectively, were also equivalent for patients and controls. However, we found that killing of viable bacteria and release of O2- by the patients' monocytes was significantly lower than that in cells from controls (P < .05 for both). The magnitude of differences in killing and O2- release between patients' cells and those from controls was even more profound with monocyte-derived macrophages. Enzyme augmentation with macrophage-targeted glucocerebrosidase preparation for 6 months at doses from 7.5 to 10 U/kg/wk resulted in significant increases of functional activities and O2- generation of monocytes and macrophages along with hematologic and hepatosplenic improvements. These data suggest that mononuclear phagocytes from GD patients are defective in their ability to kill bacteria and to generate reactive oxygen intermediates. Our data also suggest that enzyme substitution may improve functions of monocytes and macrophages in patients with GD that should make them more resistant to severe bacterial infection.