IL-4 causes a small decrease in Aβ deposition. This figure shows the relative amyloid-β expression (1–38,1-40,1-42) detected using a Meso Scale Discovery assay (MSD) for the AAV-GFP control and the AAV-IL-4-treated APP/PS1 transgenic mice. No statistically significant difference was seen between the AAV-GFP control and AAV-IL-4 groups, but the results show a decreasing trend (N = 8 AAV-GFP and N = 6 for AAV-IL-4). Immunostained Aβ plaques with Congo red could not be detected because the mice were only 3 months old. Compact plaques can be seen at 6 months of age.