Additional Supporting Information can be found in the online version of this article.

ANA_22230_sm_suppfig1.tif25515KSupporting Figure 1. Characterization of meningeal B-cell follicle-like structures. B cell follicle positive (F+) MS cases were defined by the presence of one or more B cell aggregates containing follicular dendritic cells, proliferating B cells, plasma cells and T cells. Initial analysis of cryosections from 11-12 snap or fixed frozen tissue blocks (4cm3; containing neocortex and preserved meninges) from frontal, temporal, parietal and occipital lobes was performed. In the first instance, haematoxylin/eosin histological assessment of meningeal and perivascular cellular infiltrates identified lymphocytic aggregates within the meninges or perivascular spaces (A). Adjacent sections from those revealing lymphocytic aggregates by histology were stained for CD20+ B cells, and dense aggregates of CD20+ B cells were analysed with a panel of markers to determine their status as ectopic lymphoid-like tissue. B cell follicle-like structures were characterised by the presence of numerous CD20+ B lymphocytes (B), CD4+ and CD8+ lymphocytes (C and D), CD35+ (E,F) and CXCL13+ (G) stromal cells/follicular dendritic cells, numerous Ig+ (Ig-G, -A, -M) plasmablasts and plasma cells (H) and proliferating Ki67+CD20+ B lymphocytes (I). The incidence of B cell follicles per case is listed in table 1. A number of F+ SPMS cases, such as MS092, contained numerous B cell follicle-like structures whilst others (e.g MS085, MS109) contained only two B cell follicle-like structures in eleven tissue blocks analysed. Follicle negative cases were confirmed by the independent assessment of a further 12-16 paraffin embedded tissue blocks taken as part of the standard neuropathological assessment performed by F.R. No significant lymphocytic aggregates were noted in the 17 follicle negative cases used in this study. A minimum of 24 tissue blocks were analysed to confirm a case as being negative for B-cell follicle-like structures. Scale bars= 50μm (A-D), 40μm (E), 20μm (G-I), 10μm (F)
ANA_22230_sm_suppfig2.tif25512KSupporting Figure 2
ANA_22230_sm_suppfig3.tif25511KSupporting Figure 3
ANA_22230_sm_supptab1.doc34KSupporting Table 1
ANA_22230_sm_supptab2.doc51KSupporting Table 2
ANA_22230_sm_supptab3.doc30KSupporting Table 3

Please note: Wiley Blackwell is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.