their association with complexes in the nucleus of the cell. Another worry with the ELISA technique is that anti-Sm antibodies have been reported in patients without SLE which would lead to over-investigating, but could be due to the quality of the antigen source used. Western blotting has a major disadvantage in that antibodies targeted against conformational epitopes can not be detected. On top of that, false positive can occur and the disease specificity is lower than other techniques. While each technique has their advantages and disadvantages, ELISA has the least severe disadvantages of potential for false positives (which are less dangerous than false negatives) and expensive. Many labs use a combination of both of these techniques to improve efficiency without sacrificing specificity. The current recommendation by European Consensus workshops is to screen for positive anti-ENAs with the ELISA technique. A more specific test such as CIEP will follow with samples that are identified as positive. The six main antigens used in immunological laboratories for detection are Ro, La, Sm, RNP, Scl-70 and Jo1, which are screened for by Ouchterlony double immuno diffusion techniques and confirmed by immunoblotting. On anti-nuclear antibody tests, these antigens have a speckled pattern. Terminology ENAs originally referred to proteins found in a saline extract of cell nuclei. Components have since been more clearly identified and in fact include many cytoplasmic molecules. The misnomer, however, has remained. These proteins are intimately associated with various RNA molecules and are thus called ribonucleoproteins, but the nomenclature used for them is often a source of confusion, Sm, Ro and La were named after the first 2 letters of the surnames of the patients in whom they were first found. Two proteins associated with Sjögren syndrome were independently described as antigens A and B, but are now known to be identical to Ro and La respectively, i.e. SS-A = Ro and SS-B = La. ENA (extractable nuclear antigen) panel tests, test for autoantibodies to proteins in the cell nucleus. The term "extractable" is derived from the ability to remove the autoantibodies from the nuclei with saline and common proteins. The method of identifying these specimens is why they are also referred to as antibodies to saline-extracted antigens. ENA Anti-ENA is a grouping of antibodies often used to screen for mixed connective tissue disease (MCTD), Sjögren's syndrome and systemic lupus erythematosus and commonly is composed of six tests: anti-Sm (for SLE) anti-RNP