Enzyme-cytochemically detectable glucose-6-phosphate dehydrogenase in human villous macrophages (Hofbauer cells)

Though various tissue macrophages possess high glucose-6-phosphate dehydrog enase (G6PD) activity, which plays an important role in their phagocytosis/ bactericidal function, the presence of this enzyme in human placental villo us macrophages (Hofbauer cells) has not been determined. We examined the ul trastructural localization of glucose-6-phosphate dehydrogenase (G6PD) in H ofbauer cells in first and second trimester placental villi, using a newly developed enzyme-cytochemistry (copper-ferrocyanide) method. Electron-dense deposits indicative of G6PD activity were clearly visible in the cytoplasm and on the cytosolic side of the endoplasmic reticulum of Hofbauer cells. Positive and negative cytochemical controls ensured specific detection of e nzyme activity. These observations indicated that Hofbauer cells abundantly possessed enzyme-cytochemically detectable G6PD activity. Hofbauer cell G6 PD may play a role in placental defense, by supplying NADPH-dependent enzym es (i.e. nitric oxide synthase or NADPH oxidase) with NADPH. This enzyme ma y also fuel Hofbauer cells with ribose 5-phosphate during their cell prolif eration and cell division. (C) 2001 Harcourt Publishers Ltd.