Auto-antibodies to anti-ENA SSA/RO (52 and 60 kDa): an auto-immunity laboratory's experience

PURPOSE: Anti-SSA/Ro and anti-SSB/La autoantibodies are frequently encountered in SLE or SGS where anti-SSA subtypes 52 and 60 kDa seems to be differently found in connection with the disease type: anti-SSA/Ro 60 kDa more frequently found in SLE and anti-SSA/Ro 52 kDa in SGS. We try to find if it was interesting in identifying these specificities for all anti-ENA screening. METHOD: The study included 162 patients' sera found anti-SSA 52 and/or anti-SSA 60 and/or anti-SSB positive among 1600 screening tests from the different hospital's services. We used two assays: first, dotblot (Innolia-Ana Update INGEN) as a screening test and second, an Elisa (ENA-LISA BMD) as confirmation. Thirty-eight control sera were found negative with dotblot. RESULTS: Only one subtype of anti-SSA (52 or 60 kD) or anti-SSB was found for 55 sera (44 anti-SSA 52, 10 anti-SSA 60, 1 anti-SSB) and 107 sera were found positive for two or more (73 anti-SSA 52 + 60 and 34 anti-SSA 52 or 60 with another anti-ENA). While anti-SSA 60 kDa alone or not was always positive with the Elisa test, neither anti-SSA 52 alone was anti-SSA Elisa's positive. Diseases associations results show a greater linking of anti-SSA 60 kDa with SLE, a frequent linking of combined reactivity anti-SSA 52/60 in SLE and SGS and a greater spreading of anti-SSA 52 kDa alone among pathological groups, showing an autoimmune disease's linking in 68%. Among SGS, 29% had only anti-SSA 52 kDa. CONCLUSION: We suggest screening specific tests for identifying anti-SSA/Ro 52 kDa reactivity which are missed by routine testing (tests using animal's antigens) and could represent an additional serum marker in Connective Tissue Diseases.