[Cytoplasmic staining pattern characteristic for anti Jo-1 antibody in HEp-2 cells]

We wished to confirm the staining pattern of HEp-2 cells by the anti Jo-1 antibody, because we found antibodies in serum with positive anti Jo-1 antibody which showed either a fibrilar cytoplasmic staining or a nuclear speckled staining pattern in indirect immuno fluorescence+ examinations using HEp-2 cells. Sera available from eight patients with PM DM (polymyositis and/or dermatomyositis) showed positive anti Jo-1 antibody in the double immuno-diffusion technique but had various staining patterns of HEp-2 cells in the immunofluorescent examination. We examined these eight sera with the immuno-blotting method utilizing whole cell extract of HeLa cells, and found the 50 kDa band from all sera tested, to which Jo-1 antigen had been reported to move. We eluted the antibody which formed the 50 kDa band from the nitrocellulose membrane and applied it on HEp-2 cells. This maneuver gave us the fine granular cytoplasmic staining of anti Jo-1 antibody on HEp-2 cells. We therefore concluded that the anti Jo-1 antibody should have cytoplasmic staining on HEp-2 cells although observers might miss it due to other types of associated antinuclear antibodies.