Figure 2.

Indirect immunofluorescence patterns of HEp-2 cells stained with anti–MDA5 positive sera. Stainings were performed on HEp-2 cells (Kallestad, Biorad) with sera from patients with anti-MDA5 Abs dermatomyositis. Top left: typical fine granular cytoplasmic staining in rare clustered cells. Top right: granular cytoplasmic pattern in all cells (which can mask the typical cytoplasmic pattern). Bottom left: nuclear speckled pattern, associated with the typical cytoplasmic pattern. Bottom right: isolated nuclear speckled pattern. Note that absence of fluorescence can also be observed with some sera.