Granules in glial cells of patients with Alzheimer's disease are immunopositive for C-terminal sequences of beta-amyloid protein.

Granular structures that are recognized by antibodies specific for the C-terminal but not the N-terminal sequences of the beta-amyloid protein (A beta) fragments are present in a subset of microglia and astrocytes in Alzheimer brain tissue. The immunohistochemical profile indicates that the A beta in these granules is truncated between the residues 17 and 31 and terminates at the residue 42 or 43. Such granule-containing glia occur only in brain areas with the heavy A beta deposits. Whether the intraglial A beta fragments accumulate as a result of phagocytosis of extracellular A beta or are formed intracellularly by glial cells from amyloid precursor protein (APP) remains unknown.