Acid lipase-esterase (4-methylumbelliferyl oleate hydrolase) of white matter localized in oligodendrocyte cell bodies

— The localization of an acid lipase-esterase which cleaves the fluorogenic substrate 4-methyl-umbelliferyl oleate at pH 5 was studied, because previous experiments has shown this activity to be reduced in the plaques of multiple sclerosis. In the human cerebellum, quantitative histochemical methods showed the activity to be relatively low in the molecular layer, compared to the granule cell layer; but the underlying white matter was the most active. In the human spinal cord, anterior horn cell bodies were richest in acid lipase, but white matter was, on a dry weight basis, as active as neuropil. Oligodendrocytes obtained in bulk from bovine white matter according to Poduslo & Norton (1972) had a specific activity up to 20 times greater than the crude myelin fraction. While it remains possible that in myelin the enzyme is in an inactive or inhibited state, the results indicate that the enzyme is localized in oligodendroglial cell bodies and suggest its use as a marker.