Que Inhibits T Cell Proliferation CD4+ cell infiltration (B, D) and more abundant myelin segements (MBP+, B) and oligodendrocytes (CC1+, D) are observed surrounding individual CD4+ cells. Scale bar A–B = 0.1 mm; C–D = 80 mm. doi:10.1371/journal.pone.0042746.g005 found in the Que treated mice suggest that Que may protect OLs from undergoing cell death, consistent with the previous findings, which report that Que may alleviate oxidative stress, neutralize free radicals or modulate the expression and localization of the pro- and anti-apoptotic genes Bax and Bcl-X(l/s) [12,15]. Nevertheless, we did not examine cell apoptosis in this case and cannot provide direct evidence to confirm this proposed mecha- nism in the current study. In trying to address the effect of Que on OL lineage, our present results demonstrate that the proliferation of NG2 positive OPCs were present in EAE mice with/without Que treatment (Figure S2), one of the prominent responses to demyelination [19]. Thus Que displays a neuroprotective capacity in EAE mice. On the other hand, Que may promote OPCs differentiate into myelin-formating OLs, especially when consid- ering the increased number of CC1+ mature OLs after Que treatment (Fig. 2, 5), combined with the previous observation that Que facilitates the maturation of newly formed OLs in cultures [14]. Given that the differentiation block of OPCs as a cause for failure of remyelination in chronic MS [20], our data suggests that the therapeutic effect of Que on EAE may be due to, at least in part, the capacity to promote OPCs differentiation into mature OLs that enhances remyelination in EAE model, similar to certain Figure 6. Que inhibits the activation of microglia/macrophages and astrocytes in spinal cord. Immunofluorescent staining with anti- CD68 and CD11b antibodies to demonstrate the number of microglia/macrophages in the EAE model with/without Que treatment, A. Numerous CD11b+ microglia/macrophages were observed in the EAE model which were greatly decreased after Que treatment. B. CD68 staining displayed a similar staining pattern after Que treatment. C. GFAP immunofluorescent staining displayed an increase in reactive astrocytes in the spinal cord, which was greatly decreased after Que treatment (N = 5, *, p,0.05). Quantification of the immunostaining is present in the bar graphs. Scale bar A– C = 0.2 mm. doi:10.1371/journal.pone.0042746.g006 PLOS ONE | www.plosone.org 8 August 2012 | Volume 7 | Issue 8 | e42746