Figure 1.
The amount of background signal with APP-KO tissue varies widely between different ELISAs.
A) The Covance Colorimetric BetaMark™ Beta-Amyloid x-40 ELISA Kit (left) and x-42 Kit (right). Both kits give a signal with APP-KO tissue that is significantly above baseline. The x-40 kit gives a signal with APP-KO tissue that is not significantly different from WT (the difference between APP-KO and WT is significant for the x-42 kit). B) The Invitrogen Aβ 40 Mouse ELISA Kit (left) and Aβ 42 Mouse ELISA Kit (right). Both kits give a signal with APP-KO tissue that is significantly above baseline, but also significantly different from WT tissue. C) The Wako β-Amyloid (40) ELISA Kit (left) and β-Amyloid (42) ELISA High-Sensitive Kit (right). Both kits give a signal with APP-KO tissue that is not statistically significant from baseline. D) Both WT and APP-KO give a similar level of background signal with an ELISA for human β-amyloid (6E10 capture antibody – left), but show a clear difference when a rodent-specific capture antibody is used (M3.2 antibody – right). E) “Signal to noise” ratio of the WT signal divided by the APP-KO signal for each ELISA. Error bars in A–D are standard error.
Figure 2.
Several β-amyloid antibodies show high non-specificity for β-amyloid by western blot.
A) Western blot with the antibody M3.2 (specific for rodent β-amyloid) using hippocampal tissue from APP-KO, WT, and APP transgenic mice expressing human APP (HuAPP695SWE). All three genotypes show a similar band pattern. B) Western blot with the antibody 6E10 (specific for human β-amyloid). All three genotypes show a similar band pattern. However, with 6E10, the APP transgenic mouse tissue shows an additional 8 kD band (presumably a human β-amyloid dimer) as well as a band near 87 kD (presumably full-length human APP). In addition, a 4.5 kDa band (β-amyloid) is detected when older mouse brain is used that has high levels of β-amyloid protein. C) Western blot with 4G8. All three genotypes also showed a similar band pattern with this antibody as well. In addition, a 4.5 kDa band (β-amyloid) is detected when older mouse brain is used that has high levels of β-amyloid protein.
Table 1.
Summary of Commercially Available Kits We Tested.