Supplementary Table 1. Molar Ratio of Aβ to Injected Antibody
A Species
Ratio
A:Antibody
Amyloid
Reductions After
IC Injection
5 g
A42 FA
20:1
None
Line 107
5 g
A42 PBS
1:190
None
Line 85
2 g
A42 FA
1:1
14%
Line 85
5 g
A42 FA
1:3
16%
Line 85
2 or 5 g
A42 TBS
1:6000
14 or 16%
Amount of
Injected Antibody
Line 107
Mouse Model
The ratio of Aβ to injected antibody was calculated as follows:
Line 107
According to Jankowsky et al, cortical homogenates of 6-month-old Line 107 mice contain
approximately 75 nmol/g Aβ42 and 40 nmol/g Aβ40 in the formic acid (FA) fraction, which
represents primarily insoluble amyloid plaques. Furthermore, cortical homogenates of Line 107
mice contain approximately 20 pmol/g Aβ42 and 20 pmol/g Aβ40 in the PBS fraction of a 6month-old mouse with the APP transgene on, which represents soluble species of Aβ (22). It
should be noted that production of Aβ is suppressed in Line 107 mice used in our study. On
average, a mouse cortex weighs about 0.225 g, measures approximately 7 mm from the frontal to
the posterior cortex in the saggital plane (25), and the injection was performed in 1 hemisphere.
Line 107 mice received 2 injections 1 mm apart, and from the measurement of antibody spread
in Line 85 mice (on average, 0.6 mm in either direction), it can be estimated that antibody spread
approximately 2.2 mm in Line 107 mice. Hence, the molar ratio of formic acid-extracted Aβ42
to injected antibody is:
0.225 g × 75 nmol/g = 16.88 nmol Aβ42/cortex
16.88 nmol × (2.2 mm antibody spread × 0.5)/7 mm = 2.65 nmol Aβ42 in injected region
Antibody: 5 μg/ injection site
10 μg/150,000 g/mol = 66.6 pmol antibody in injected region
Each antibody has 2 epitope binding sites, thus, the injected antibody can theoretically bind 133
pmol Aβ42.
2650 pmol Aβ42 / 133 pmol antibody ≈ 20:1 Aβ42:IgG
1
Line 85
According to Garcia-Alloza et al (24), homogenates from hemispheres of 12-month-old Line 85
mice contain approximately 1009 pmol/g Aβ42 and 412 pmol/g Aβ40 in the FA fraction
representing the insoluble amyloid plaques, whereas the TBS fraction contains 0.22 pmol/g
Aβ42 and 0.67 pmol/g Aβ40 (soluble Aβ). Note that the hemibrain homogenates will result in a
slight underestimation of hippocampal Aβ levels since these homogenates will include
cerebellum and midbrain where amyloid plaques are less frequent than in the hippocampus. On
average, a mouse brain weighs about 0.4 g (35), measures approximately 11.5 mm from the
frontal cortex to the posterior cerebellum in the saggital plane (25), and the injection was
performed in one hemisphere (antibody spread 1.2 mm). The Line 85 mice were injected with
either 2 or 5 μg of antibody which corresponds to approximately 27 or 133 pmol of antibody
binding sites available to bind Aβ, respectively. Hence, the molar ratio of formic acid
extractable Aβ42 to injected antibody is:
0.4 g × 1009 pmol/g = 404 pmol Aβ42/brain
For 2 μg of injected antibody:
404 pmol × (1.2 mm × 0.5)/11.5 mm = 21 pmol Aβ42 in injected region
21 pmol Aβ42 / 27 pmol antibody ≈ 1:1 Aβ42:IgG
For 5 μg antibody/injection site:
404 pmol x (2.2 mm x 0.5)/11.5 mm = 39 pmol Aβ42 in injected region
39 pmol Aβ42 / 133 pmol antibody ≈ 1:3 Aβ42:IgG
Reductions in amyloid burden after IC injection are quantified by area fraction of
immunoreactivity as described in Fig. 1 and Fig. 2.
2