Fig. 2

Binding of ITPR1-IgG/anti-Sj to cerebellar sections (a–c; a: staining of the Purkinje cell layer and the molecular layer; b: staining of axonal cross sections in the cerebellar white matter) and to ITPR1-transfected HEK293 cells (d) but not to mock-transfected HEK293 cells (e). Green fluorescence (FITC) indicates binding of patient IgG; red fluorescence (AF568) indicates binding of patient IgG of the IgG2 subclass; blue fluorescence corresponds to cell nuclei stained by 4′,6-diamidino-2-phenylindole. Note that the vessel-associated staining present in panel (c) is caused by non-specific cross-reactivity of the detection antibody with primate IgG that has penetrated the vessel walls post mortem during preparation of the brain specimen, was therefore present also after incubation of the sections with PBS instead of serum (not shown), and does not indicate the presence of anti-vessel antibodies in our patient; no such cross-reactivity was seen when using another, whole-IgG-specific secondary antibody (a, b)