Anti-Jo-1 antibodies in polymyositis or dermatomyositis: evaluation by ELISA using recombinant fusion protein Jo-1 as antigen

We evaluated an enzyme-linked immunosorbent assay (ELISA) for detectinganti-Jo-1 antibodies in patients with polymyositis (PM) or dermatomyositis(DM) by use of the recombinant fusion protein Jo-1. Sera from 64 patientswith PM or DM, from 80 patients with other connective tissue diseases, andfrom 64 healthy subjects matched for age, sex and race, were studied by theELISA and by the double immunodiffusion (DID) method. Eight patients withmyositis (six PM, one DM and one DM with malignancy) with positiveanti-Jo-1 by DID also showed positive results by the ELISA method, whereasfive patients with positive anti-Jo-1 by this ELISA showed negative resultson DID. One of the five had non-specific results. The incidence of positiveresults for anti-Jo-1 with the ELISA (18.8%) was greater than that for DID(12.5%), but the difference was not statistically significant. All patientswith positive results for anti-Jo-1 by DID were also positive by the ELISA.The ELISA system with the recombinant Jo-1 antigen was useful in thedetection of anti-Jo-1 antibodies in patients with PM/DM.