Could Apolipoprotein D be a Neuronal Marker of Necrobiosis?

Abstract

Apolipoprotein D (apo D) is a member of the lipocalin family that is involved in the transport of small hydrophobic ligands, although its physiological functions are yet well known. Using an anti-human apo D antibody and PAP immunocytochemistry on normal human cerebellum tissue, we found that a marked increase in apo D immunoreactivity occurs in human cerebellum during aging. Besides increased immunoreactivity levels in glial cells, we observed a major number of stained Purkinje cells. Morphometric studies were performed to study if quantitative deifferences exist between apo D positive and negative Purkinje cells. These 2 neuron populations presented the same morphological characteristics, and there were no structural evidences of cell injury or death. The data showed significant differences (p < 0.05) for mean cellular area and circular factors; neurons containing apo D were bigger and more rounded than neurons without apo D. These rescllts could be better understood if apo D were considered a marker of necrobiosis more than a marker of irreversible cell death. (The J Histotechnol 24:29, 2001)Submitted: May 15,2000; Accepted with revisions: December 1, 2000