Counterimmunoelectrophoresis, ELISA and immunoblotting detection of anti-Ro/SSA antibodies in subacute cutaneous lupus erythematosus. A comparative study.

Patients with subacute cutaneous lupus erythematosus (SCLE) have circulating antibodies to Ro/SSA directed to two antigenically distinct ribonucleoproteins of 60 kDa and 52 kDa. Three laboratory tests may be used to detect anti-Ro/SSA antibodies: counterimmunoelectrophoresis (CIE), enzyme-linked immunosorbent assay (ELISA) and immunoblotting (IB). Their relative efficacy and clinical correlations were ascertained. We determined anti-Ro/SSA antibodies with CIE, with two different ELISA methods (ELISA 1 and 2) and with IB in 29 SCLE patients. Anti-52 kDa and -60 kDa Ro/SSA antibodies were also assayed with IB. In addition, we determined antinuclear antibodies with indirect immunofluorescence, anti-Sm, anti-RNP, anti-La/SSB and anti-Ro/SSA antibodies with CIE and ELISA, and anti-nDNA and cardiolipin antibodies using an ELISA method. CIE detected anti-Ro/SSA antibodies in 22 patients while ELISA 1 and 2 did so in 17 and 18 patients, respectively. In five patients, IB revealed a reactivity to 60 kDa polypeptides and in two, a reactivity to 52 kDa polypeptides. Of these seven patients, four had a myocardial infarction. Of these, two reacted to the 52 kDa antigen and two to the 60 kDa antigen. A combination of techniques was often needed to detect all specificities. ELISA proved to be very specific and sensitive. The IB technique detected a group of patients with myocardial infarction. A case-control study is needed to confirm the data of cardiac involvement.