Detection of antinuclear antibodies: a survey done by the European Organsation for External Quality Assurance Providers in Laboratory Medicine.

Introduction: A questionnaire was sent to immunology laboratories worldwide by the European Organisation for External Quality Assurance Providers in Laboratory Medicine to evaluate current practice with regard to how antinuclear antibodies (ANAs) are routinely tested in clinical laboratories.

Methods: In total, 494 questionnaires were returned from 44 countries. Of these, 379 provided sufficient information to be included in the analysis.

Results: Indirect immunofluorescence on HEp-2 cells is still the most common method to test ANAs and is used by 330 of our 379 respondents. The most common (60%) screening dilution is 1:80, followed by 1:160 (15%) and, in equal amounts, 1:40 and 1:100 (8% each). In most laboratories, ANA-positive samples are further diluted to an end titer of 1:1280 (40%), 1:2560 (21%), 1:5120 (16%), or 1:640 (19%). An increasing number of laboratories (178/330) use the International Consensus on ANA Patterns (ICAP) nomenclature to describe the immunofluorescence pattern on HEp-2 cells. In countries with the most respondents, the percentage of laboratories accredited to EN International Organization for Standardization (ISO) 15189 (in Britain, BS EN ISO 15189, which is a British standard as well as a European standard as well as an ISO standard with identical content) is between 8% (Belgium) and 60% (France). There was no difference in the portion of accredited laboratories between university hospitals, nonuniversity hospitals, and private laboratories.

Discussion: Indirect immunofluorescence continues to be the most frequently used technique for ANA testing in laboratories. The increasing number of laboratories using the ICAP classification reflects an ongoing harmonization of describing ANA patterns on HEp-2 cell substrates.