Histochemical investigations on the localization of the purple acid phosphatase in the bovine spleen.

The localization of the purple tartrate-resistant, iron-containing acid phosphatase in the bovine spleen was studied by enzyme histochemistry at the light and electron microscopic levels as well as by immunohistochemistry. The purple phosphatase was localized only in lysosome-like-organelles of cells belonging to the reticulo-phagocytic system. The same cells were identified as containing large iron(III)-deposits as ferritin in homogeneously granular accumulations and freely in the cytoplasm, or as hemosiderin in siderosomes. The phagocytosing cells containing purple phosphatase and ferritin often had close contact with clusters of aged and deformed erythrocytes. A possible catabolic role of the purple enzyme as a phosphatase degrading phosphoproteins of the erythrocyte membrane and the cytoskeleton was assumed.