The distribution of Alz-50 immunoreactivity in the normal human brain

Alz-50 is a monoclonal antibody that recognizes normal tau proteins as well as phosphorylated tau proteins that are associated with paired helical filaments in Alzheimer's disease. To establish an accurate baseline for future pathological studies, we examined the distribution of Alz-50 immunoreactivity in normal human brain from infancy to senescence. We found extensive staining patterns of somata and axonal profiles in the striatum, amygdala, hypothalamus, brainstem and spinal cord in all normals at all ages. Similar normal staining patterns were seen in the brains of patients who had suffered trauma, tumors, cerebral infarcts, grade 1 periventricular hemorrhages, and in those who had suffered from amyotrophic lateral sclerosis, Parkinson's disease, multi-systems atrophy and Shy-Drager syndrome. An absence of cell body staining and only minimal axonal staining was noted in the same brains with immunocytochemistry using PHF-1, a monoclonal antibody generated against paired helical filament proteins from Alzheimer brains. The characteristic staining pattern of Alz-50 in normal brains is substantially more extensive than has previously been recognized. This pattern, which presumably describes a specific class of tau proteins, must be distinguished from the pathological staining observed in neurodegenerative diseases.