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In 1994, the French National Quality Control Group for Hematology, Etalonorme, conducted a large-scale interlaboratory survey concerning the detection of lupus anticoagulants (LA) involving all the 4,500 French laboratories. Each laboratory received the same batch of a lyophilized citrated plasma (94B3) prepared from a patient with LA that had been confirmed by all the techniques used in the intralaboratory study. In the interlaboratory survey, the screening test was activated partial thromboplastin time (A FIT); mean A KIT calculated from the results reported by 4,029 labs was prolonged (clotting ratio = 1.44) with a large dispersion (coefficients of variation = 18.8%). APTT of the mixture 94B3 + Normal plasma were performed by 2,698 laboratories. No correction of APTT was obtained (R = 1.36, Rosner index = 24) with a wide variation between reagents (17 < Rosner index < 39). OnlyThis report originated from the first French national survey on lupus anticoagulants (LA). Lupus anticoagulants are heterogeneous autoantibodies directed against anionic phospholipids or against a protein-phospholipid complex 1 " 3 and constitute one member of the family of antiphospholipid antibodies. These acquired inhibitors of coagulation are described in patients with systemic lupus erythematosus or related autoimmune diseases and in otherwise healthy persons. 4,5 Their presence is closely associated with the occurrence of arterial and venous thromboembolism, thrombocytopenia, fetal loss, valvular heart disease, and dermatologic manifestations.6 7 The thrombotic predisposition is sustained by numerous relevant pathogenetic mechanisms, including interference with numerous compounds of the hemostasis pathways. 8 The Lupus Anticoagulant/Antiphospholipid Antibody Subcommittee published recommendations for testing and identification of LA in 1991 9 and a revision in 1995. In France, the national quality control group, Etalonorme," conducted an interlaboratory survey concerning LA detection involving all 4,500 French laboratories. The aim of the survey was to evaluate, on a large scale, the level of French laboratory performances and to check the sensitivity and specificity of the different tests and reagents used. The final goal was to draw up an educational program concerning LA for French biologists, and to make recommendations for testing.All the laboratories received the same batch of commercial lyophilized human plasma containing an LA. Biologists had to perform the tests with their own reagents and to follow the recommended procedure for testing and detection of LA (Appendix). The screening test was activated partial thromboplastin time (APTT), the inhibitor was identified by mixing studies, and a confirmatory test had to be chosen from a proposed list including tests performed with a reduced or an augmented amount of phospholipids. The results indicate that the reagents have different sensitivities. Seventy percent of the laboratories suspected the presence of LA, but only 15% performed the confirmatory test. MATERIALS AND METHOD...

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As IgE synthesis and HLA-DR induction may represent indirect indicators of the activation of the Th2 and Th1 subsets, association of these two simple tests could be interesting for the routine assessment of the mechanisms of inflammatory ocular surface diseases.

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