Specific testing for “isolated” anti-52 kDa SSA/Ro antibodies during standard anti-extractable nuclear antigen testing is of limited clinical value

Abstract

Aim:To ascertain whether specific testing for “isolated” anti-52 kDa SSA/Ro antibodies (a-SSA/Ro52) during standard anti-extractable nuclear antigen (ENA) testing is clinically useful.Methods:1438 consecutive sera submitted for anti-ENA testing over 1 year were evaluated for a-SSA/Ro52 using various assays.Results:7 of 1438 (0.48%) patients were found to have a-SSA/Ro52 without SSA/Ro60 antibodies. Subsequent testing detected a further five patients. Clinical follow-up was possible in 10/12 patients. 2 of these 10 patients had evidence of primary Sjögren’s syndrome (SS) and one had systemic lupus erythematosus (SLE), with sicca symptoms and abnormal Schirmer’s tests. Five other patients had sicca symptoms, of which four had abnormal Schirmer’s tests.Conclusions:“Isolated” anti-52 kDa SSA/Ro antibodies were detected in approximately 0.5% of standard anti-ENA requests, in which their presence was generally not associated with underlying SS or SLE. In view of the increased testing complexity and costs in detecting and confirming these antibodies, specific testing for isolated a-SSA Ro52 antibodies during standard anti-ENA testing seems to be of limited clinical value in a non-obstetric population.

Diagnostic utility of anti-Ro52 detection in systemic autoimmunity

“…In our hands, the LIA appeared to be a simple and reliable method to detect anti-Ro52 reactivity. The prevalence of monospecific anti-Ro52 reactivity (12.7%) in our selected patient cohort was considerably higher than the previously reported figures of 0.5%2 and 1%1 in serial laboratory samples tested, possibly reflecting selection bias. Triple reactivity to Ro52, Ro60 and La was more commonly found in pSS than SLE as previously reported,8 which may be explained by the higher specificity of anti-La for pSS.…”

“…The diagnostic utility of ‘monospecific’ or ‘isolated’ anti-Ro52 autoantibodies (anti-Ro52 reactivity without concomitant anti-Ro60 reactivity) is controversial1 2 and has been shown to have low diagnostic value in evaluation of autoimmune diseases 3. Recent evidence for their clinical relevance comes from a study in patients with idiopathic inflammatory myopathies (IIM), where anti-Ro52 autoantibodies were the most common immune marker detected and associated with a favourable response to prednisone 5.…”

“…Since anti-Ro52 autoantibodies are not disease specific, we sought to determine their prevalence in various selected autoimmune diseases, as opposed to testing serial laboratory samples sent for detection of antibodies to extractable nuclear antigens (ENAs), which has been reported to be of limited clinical value 2. The aims of our study were to determine the prevalence and diagnostic utility of detecting monospecific anti-Ro52 (defined as an immune response against Ro-52 antigen in the absence of reactivity to Ro-60 antigen) reactivity in selected systemic autoimmune diseases by the Euroline ANA profile line immunoassay and its correlations with other serological markers.…”

Clinical associations of the positive anti Ro52 without Ro60 autoantibodies: undifferentiated connective tissue diseases

“…The true prevalence of Ro52+Ro60− is unknown given that negative ANA samples are not routinely checked for ENA. In addition, the sensitivity of assays for detecting ENA varies 14. Therefore, if anti Ro52 antibodies are suspected, another assay method containing Ro52 antigens should be used for counter checking.…”

Neonatal Lupus

“…Certain laboratories identify only anti-Ro60, while others test antiRo60 and anti-Ro52. Isolated anti-Ro52 is extremely uncommon [ 101 ] and thus a positive anti-Ro60 fi nding is suffi cient to place a pregnancy at risk. A negative antiRo60 fi nding is likely suffi cient to rule out NL, although certain investigators suggest specifi c testing of anti-Ro52, which may or may not be available commercially.…”