Figure 2. Iron is found inside microglia/macrophages in marmoset EAE lesions more than 6 weeks old.

(A) Marmoset EAE lesions, categorized based on age, accumulate iron deposits only when they are older than 6 weeks; such deposits are not seen in healthy white matter (WM). (B) Double-staining in lesions older than 6 weeks shows that iron is found predominantly inside perivascular Iba1⁺ microglia/macrophages, but not in GFAP⁺ astrocytes. Ferritin and Iba1 double-staining shows localization of ferritin within Iba1⁺ cells in a similar distribution to the localization of iron. (C) Iron⁺ lesions are significantly older than iron^- lesions (Mann-Whitney test; distributions are summarized by mean and standard error). (D) Graphical representation of EAE lesions, categorized based on age and the presence or absence of intralesional iron. (E) Graphical representation of the proportion of lesions that are iron⁺ or iron^-, plotted as a function of lesion age (Fisher’s exact test). (F) Histogram of the distribution of iron⁺ lesions and the time difference between when the lesion was first detected on PDw and the hypointense signal was first detected on T2*w MRI. Scale bars: 100 μm. ****P < 0.0001. Representative lesions from marmosets 9, 10, 12, and 13.