Temporal cortical homogenates containing 60μg of total protein from case AD1 and seven other AD cases were separated by SDS-PAGE and immunoblotted with antibody 6E10 to the N-terminal region of Aβ. A preparation of synthetic Aβ42 (10 ng) is in the far right lane, as a positive control. Strong bands of monomeric Aβ were detected in all AD cases examined. Light bands corresponding to Aβ dimers were detected only in some of the AD lanes under these conditions. In AD1, 6E10 immunoblotting revealed high levels of dimeric and trimeric Aβ, as well as several higher molecular weight, Aβ-immunoreactive bands between 17 KDa and 44KDa. Note that 6E10 also recognizes the Aβ epitope in APP (top band), which was not increased in AD1. When the total protein content in AD1 temporal cortex was diluted to 6.78μg to normalize total Aβ levels to those seen in the comparison AD cases, the higher molecular weight bands, though lighter, were still detected by 6E10 immunoblot analysis, indicating that the presence of these bands cannot be accounted for simply by the overall quantity of Aβ in AD1 temporal cortex (data not shown).