Staining pattern produced by anti-Ro52 antibodies

Human serum containing antibodies directed against Ro52 stained the cytoplasm of HEp-2 cells. To demonstrate the cytoplasmic staining pattern produced by these antibodies, a plasmid encoding Ro52 fused to green fluorescent protein (GFP) was expressed in HEp-2 cells and was stained with mouse anti-GFP (green, panel A). Two of the five cells in the field were successfully transfected with the plasmid (indicated by white arrows). Human anti-Ro52 antibodies stained the cytoplasm of all the HEp-2 cells in the field, but staining was especially intense in cells over-expressing Ro52-GFP (red, panel B). DAPI staining (blue) in panel C indicates the location of nuclei.