Background

Polymyositis (PM) and dermatomyositis (DM) are inflammatory, autoimmune mediated disorders of the connective tissue with unknown etiology. They primarily damage skin and/or muscles, but may also affect other organs as e. g. the lung. Without treatment (standard therapy is immune suppression), they tend to develop into a life-threatening state. Since immunosuppressive agents are known to cause considerable side effects, early diagnosis of PM/DM is essential, in order to keep their dosage as low as possible.

A striking feature of PM/DM is the occurrence of antibodies to aminoacyl-tRNA synthetases; functionally related but immunologically distinct enzymes. About 30 % of all myositis patients carry antibodies against histidyl-tRNA synthetase, a 100 kDa dimeric antigen, located in the cytoplasma and known as Jo-1.

Technical information

The EULISA Jo-1 IgG is intended for the quantitative or qualitative determination of IgG antibodies in human serum, directed against Jo-1. The antigen used is a highly purified preparation of human histidyl-tRNA synthetase, expressed by baculovirus infected insect cells. The test is fast (incubation time 30-30-30 minutes) and flexible (break apart wells, ready-to-use reagents). Six calibrators allow quantitative measurements; a negative and a positive control are used to check assay performance.