ALZ-50 Staining of Enteric Neurons in Down Syndrome in Infants and Children

The monoclonal antibody ALZ-50, known to stain degenerating cerebral neurons in Alzheimer disease (AD), demonstrates a protein, A668, that is a modified form of the normal microtubule-associated protein, tau. We have stained 5- mu m sections from paraffin blocks of formalin-fixed tissues from various levels of the gastrointestinal tract of 13 DS patients, from 20 weeks of gestational age to 14 years, with biotinylated mouse monoclonal ALZ-50 antibody. ALZ-50-positive neurons were not seen in the Meissner or Auerbach plexuses in any of the sections from five patients with DS who were 20 gestational weeks to 4 months of age, whereas positive neurons were found in 22 of 49 loci (45%) in DS patient 14 months to 14 years of age. Whether the proportion of more strongly ALZ-50-positive enteric neurons in either Auerbach plexus rises further over the age period from 14 years to the time of onset of the AD-like neurologic changes of DS at age 35-40 years, or thereafter, will require further study.