Augmentation of macrophage candidactdal function by recombinant human granulocyte-monocyte colony stimulating factor (rhgm-csf) and myeloperoxidase (rhMPO)

We found earlier that monocytes, rich in MPO, killed C.albjcans at a significantly higher rate and degree than did monocyte-derived macrophages known to lack MPO (J.ImmuQol. 146:2783). We hypothesized, therefore, that the capacity of macrophages to kill Candida might be retained in the presence of MPO. In this study, the ability of rhMPO to augment the fungicidal activity of resident and rhGM-CSF-activated macrophages for C.albicans was evaluated. rhMPO was produced in transfected and amplified Chinese hamster ovary cells and purified by a combination of ion exchange and metalchelate chromatography. Addition of rhMPO (concentrations: 0.8, 1.6, 3.2, and 6.4 U/ml) to suspensions of resident macrophages and serum opsonized C.albicans resulted in significant increases in the killing capacity of Candida at concentrations of 3.2 U/ml and 6.4 U/ml (p<0.05for each). Preincubation of macrophages with rhGM-CSF for 48 h induced a concentration dependent increase in release of Superoxide anion and killing of opsonized C.albicans; maximal activity for these functions occured at the concentration of 200 U/ml (10±5nmol and 28J4nmolsuperoxide released by 2×106 resident and activated cells, respectively; 17±2 % and 32±4% killing by resident and activated cells, respectively), with no appreciable increase being achieved by treatment of cells with 300 to 1000 U/ml rhGM-CSF. Addition of rhMPO (concentrations: 0.8 to 6.4) to the phagocytix mixture further increased the candidacidalcapacity of rhGM-CSF-activated macrophages (p< O.OSat each concentrations used). These data indicate that exogenous rhMPO augments candidacidal capacity of both resident and rhGM-CSF-activated macrophages with a more profound effect on activated cells. These data suggest that rhMPO might be effective in the treatment of invasive candidiasis.SCOPUS: ar.j