Figure 3.

Infiltrated CD3 positive cells in 18-month-old PS1xAPP hippocampus predominantly developed a Th2 response. A, Double labeling for anti-CD3 and Congo Red immunohistochemistry demonstrated the infiltration of CD3-positive cells in hippocampus of 18 month PS1xAPP mice (a2, a4), whereas the presence of CD3 cells was scarce in 18 month WT (a1) or in 6 month PS1xAPP mice (a3). The infiltrated CD3 cells were preferential, but not exclusively located around some Aβ plaques (a4). B, The expression of different interleukin mediators, IFN-gamma and TGF-β1, considered representative of the different adaptive T-mediated immune responses, were determined in 6- and 18-month-old WT and PS1xAPP mice (n = 10 per group). Compared with WT (using one-way ANOVA), only the expression of IL-10, TGF-β and, more prominently, IL-4 were significantly induced in PS1xAPP mice. Interestingly, the expression of IL-4 also displayed a significant increased in 6-month-old PS1xAPP. C, At 6 months of age (c1), IL-4 punctate immunostaining was concentrated around Aβ plaques. Double GFAP-IL4 immunolabeling and confocal laser microscopy (c2–c4) revealed that activated astroglial cells expressed this interleukin. In 12-month-old PS1xAPP mice, all infiltrating CD3-positive cells were also immunoreactive for anti-IL4 (c5–c7). Scale bars: a1–a3, 200 μm; a4, 100 μm; c1, 25 μm; c2–c4, 5 μm; c5-c7, 5 μm.