... PM/Scl-100(Diarect AG, Freiburg, Germany), was expressed in Escherichia coli and purified via a His-tag, and the quality wasensured by immunoblot and checkerboard analysis of positive and negative sera in the ... providing clinically defined sera, Mark L Fritzler (University of Calgary, Canada) for technical assistance with the addressable laser bead immunoassay and Wilma Vree Egberts (Radboud University ... MJF and RR deliveredclinically defined sera, advised MM in evaluating the clinicalpart of this study and contributed to the preparation of themanuscript. CD organized the analysis of anti-PM/Scl...