Glucose-6-phosphate dehydrogenase and mouse Kupffer cell activation: an ultrastructural dual staining enzyme-cytochemical study

Glucose-6-phosphate dehydrogenase (G6PD) plays an important role in Kupffer cell function, especially in phagocytosis activity. Although it was suggested that Kupffer G6PD may be upregulated in Kupffer phagocytosis/activation, direct morphological evidence has been lacking. Acid phosphatase (ACP), a representative lysosomal enzyme, can be used as a cytochemical marker for phagocyte activation. Using an ultrastructural enzyme-cytochemical dual staining method, I simultaneously localized G6PD and ACP activity in mouse Kupffer cells on a cell-by-cell basis, and examined whether or not cytochemically detectable G6PD activity increases in phagocytosing/activated mouse Kupffer cells. Glucose-6-phosphate dehydrogenase labelings were observed in the cytoplasm and on the cytosolic side of the endoplasmic reticulum, and ACP labelings were seen in the lysosomes. In phagocytosing Kupffer cells, in which ACP deposits were observed not only in the lysosomes but also on the phagosomal membranes and phagosomal contents, G6PD labelings were denser than dormant Kupffer cells. Enzyme-cytochemically detectable G6PD activity increases in phagocytosing/activated mouse Kupffer cells. Kupffer cell G6PD, activated in phagocytosing Kupffer cells, may play an important role not only in liver defense but also in liver disease pathogenesis/pathophysiology.