Characterization of arachidonate 12-Lipoxygenase found in the liver of mongrel dog and its immunohistochemical localization in neutrophils

: The cytosol fraction of non-parenchymal cells isolated from the liver of adult mongrel dogs converted arachidonic acid to 12S-hydroxy-5,8,10,14-eicosatetraenoic acid. The arachidonate 12-lipoxygenase enzyme reacted with linoleic and alpha- and gamma-linolenic acids as well as arachidonic acid. The enzyme was immunoprecipitable with an antibody against the leukocyte 12-lipoxygenase, but not with an antibody against the platelet 12-lipoxygenase. By immunohistochemical observation with anti-leukocyte 12-lipoxygenase antiserum, hepatocytes, Kupffer cells and sinusoidal endothelial cells were not immunostained, but a large number of neutrophils located in sinusoidal cavities were positively stained. The 12-lipoxygenase activity thus detected may be attributed predominantly to the neutrophils appearing in sinusoidal cavities rather than the non-parenchymal cells in the liver of mongrel dog upon infection. In agreement with this finding there was essentially no neutrophil accumulation in the liver of Beagle dog which had no bacterial and parasitic infection.