Figure 4.
CD45-deficient primary microglia have impaired Aβ1-42 phagocytosis. CD45-sufficient or -deficient primary microglial cells were prepared from neonatal mice and treated with agonistic CD45 antibody (2.5 μg/ml) or isotype control IgG (data not shown) in the presence of 1 μm aged FITC–Aβ1-42 for 60 min. a, Cellular supernatants and lysates were analyzed for cell-associated (left) and extracellular (right) FITC–Aβ1-42 using a fluorometer. Data are represented as the relative fold of mean fluorescence change (mean ± SD), calculated as the mean fluorescence for each sample at 37°C divided by mean fluorescence at 4°C (n = 6 for each condition presented). b, In parallel experiments, primary microglia were treated as in a but were then fixed and imaged in independent channels using a confocal microscope equipped with Normarski optics. Merged images shown on the right reveal localization of Aβ1-42 within the cytoplasm of CD45-sufficient microglia but on the cell surface of CD45-deficient cells. *p < 0.05, **p < 0.01.