Figure 2

Release of N-terminally truncated Aβ-peptides is induced by polystyrene beads and acetylated LDL but not by LPS. CD14⁺ monocytes were negatively isolated by MACS and kept in serum-free AIM-V medium in ultra low binding culture vessels. Following stimulation for 72 h cell culture supernatants were collected and subjected to immunoprecipitation with mab 1E8-preactivated magnetic beads. Released Aβ peptides were assessed by isoelectric focusing on linear IPG strips (pH4-7) and subsequent Aβ-SDS-PAGE (2D-Aβ-WIB). (A) shows the separation of the following synthetic standard Aβ peptides: Aβ_1-37, Aβ_1-38, Aβ_1-39, Aβ_1-40, Aβ_1-42 as well as Aβ_2-40 and Aβ_2-42. For a better orientation, synthetic Aβ_1-37, Aβ_1-38, Aβ_1-39, Aβ_1-40, Aβ_1-42 were additionally separated one-dimensionally on the right side of each gel. The following figures show 2D-Aβ-WIBs from supernatants of untreated cultures (B) or cultures stimulated with LPS 10 ng/ml (C), acLDL 10 μg/ml (D) and 1 μm carboxylated polystyrene beads 4*10⁷/ml (E) that were processed as described above. In (F), the LPS stimulus was combined with polystyrene beads at the concentrations used in (C) and (E), respectively. Distinct Aβ reactive spots are indicated by characters and by the respective pI values. Note the proportional increase of released N-truncated Aβ peptides migrating at pI 6.37 upon phagocytosis (D, E, F).