Cortical Lewy body-containing neurons are pyramidal cells: laser confocal imaging of double-immunolabeled sections with anti-ubiquitin and SMI32.

To characterize neurons containing cortical Lewy bodies (LBs), vibratome sections of the superior temporal cortex from eight patients with the LB variant of Alzheimer's disease (LBV) were double-immunolabeled with anti-ubiquitin (a marker of LBs) and anti-nonphosphorylated neurofilament (SMI32; a marker of pyramidal cells) or parvalbumin (PV; a marker of interneurons) and were viewed with a laser-scanning confocal microscope. Almost all (96.1%) the LB-containing neurons were positive for SMI32, but not for PV. Furthermore, the average numbers of SMI32-immunoreactive neurons in layers 3 and 5 were 63% and 77% of those in controls, respectively. PV-immunoreactive neurons showed a greater than 40% decrease. These findings indicate that cortical LB-containing neurons are pyramidal cells and suggest that in LBV, there may be some differences in the degenerative processes effecting pyramidal cells and interneurons.