Purification and characterization of Lewy bodies from the brains of patients with diffuse Lewy body disease.

Lewy bodies (LBs) are the pathological hallmarks of degenerating neurons in the brains of patients with Parkinson's disease and diffuse Lewy body disease. We developed a novel purification procedure for LBs using sucrose density separation followed by fluorescence-activated particle sorting, and we raised > 15 monoclonal antibodies to LBs purified from diffuse Lewy body disease brains. The monoclonal antibody that stained the largest number of LBs most intensely did not recognize ubiquitin in free or monoubiquitinated forms nor the ubiquitin conjugating enzymes, but it did react with polyubiquitin chains as well as with high molecular weight polyubiquitinated LB-derived proteins. Thus, these results suggest that LBs contain polyubiquitin chains. Although polyubiquitination of LB proteins may trigger ubiquitin-proteasome proteolytic pathways, the incomplete activation of these pathways could play a mechanistic role in the formation of LBs in neurodegenerative diseases.