Figure 3.

Formation of self‐aggregating structures of MOG34‐56 and citrullinated derivatives in overnight incubation with or without human EBV‐infected B cell (EBV‐BC) line. Native MOG34‐56 (row A) and the citrullinated versions MOGcitr41,46 (row B) and MOGcitr46,52 (row C) were fed to EBV‐BC. The peptides were labeled with purple fluorochrome via click chemistry. The cells were stained with DAPI (blue) to visualize nuclei and with anti‐LC3 (autophagosomes) or anti‐HLA‐DR (B cell membrane antigen) mAb (both green). The figure shows low background LC3 staining of EBV‐BCL incubated without peptide (A1). Feeding MOG34‐56 increases LC3 staining (A3,4) indicating upregulation of autophagy. The peptide appears in spherical structures (A3,4 purple) of varying size. Citrullinated MOGcitr41,46 peptide incubated without cells spontaneously forms medium‐sized aggregates (B2). When incubated with EBV‐BC at a low dose similar spherical structures as the native peptide (B3). Containment in an MHC class II+ staining capsule (B5) suggests that the spheres originate from the EBV‐BC. Incubates of EBV‐BC with high dose MOGcitr41,46 (B4) contain large peptide aggregates and virtually no B cells, indicating that these may have been killed, as confirmed in reference. ⁵⁷ MOGcitr46,52 peptide incubated without EBV‐BC (C2) or with EBV‐BC (C3,4) spontaneously forms much larger aggregates than in B2 and at a much higher rate (see Ref. [57]), but spherical structures were not found.