Detection of endogenous Aβ protofibrils using SP-PLA. Brain homogenates from five transgenic ArcSwe mice expressing elevated levels of protofibrils and five control mice were examined using SP-PLA (A) and the mAb158 ELISA (B). The blue and red rectangles indicate the median for control and transgenic-mice, respectively, revealing a significant difference between the two groups of mice. (C) Results of SP-PLA of brain homogenates from transgenic and non-transgenic mice, spiked in 10% human CSF. Error bars indicate standard deviations from the mean for triplicates for each reaction.