Ballooned neurons in several neurodegenerative diseases and stroke contain alpha B crystallin.

alpha B crystallin is a protein which has homology with the small cell stress proteins. A characterized antibody to residues 1-10 of alpha B crystallin was used to immunostain tissues containing ballooned (chromatolytic, achromasic) neurons. The tissues included two cases of classical Pick's disease, one case of dementia with swollen achromasic neurons in the cortex, two cases of Alzheimer's disease with large numbers of ballooned neurons, two cases of motor neuron disease, four cases of cortico-basal degeneration, and four cases with areas of brain showing swollen neurons adjacent to recent cerebral infarcts. The anti-alpha B crystallin showed strong diffuse cytoplasmic immunoreactivity of swollen cortical neurons in all the diseases. Astrocytes and oligodendroglial cells were also stained in normal tissues as previously described. Weak diffuse immunoreactivity with an antibody to ubiquitin-conjugates was also seen in the swollen neurons from cases of neurodegenerative disease but not following infarction. Ballooned neurons have been shown to contain phosphorylated neurofilament epitopes not normally present in the perikaryonal region. The presence of alpha B crystallin in ballooned neurons, together with previous data which also indicate its close association with intermediate filaments, suggest that alpha B crystallin may be involved in aggregation and remodelling of neurofilaments in disease. The presence of alpha B crystallin in neurons at the edge of areas of cerebral infarction is likely to reflect cells which are regenerating following damage; its detection may therefore be a marker for such cells. On a practical level, the antibody greatly facilitates the localization of such abnormal neurons in diagnostic histology.