INTRODUCTION: Recently, arrays have become available that allow the simultaneous analysis of several anti-citrullinated protein antibody ( @entity7134 ) reactivities using distinct citrullinated peptides. Such assays are designed for exploratory studies. The interpretation of positive antibody reactivities can best be made if the diagnostic and prognostic value of a multiplex array in an early @entity625 setting is known and if the multiplex-positive @entity1 who are negative according to three commonly used commercial @entity7134 assays are characterized. METHODS: Using Thermo Scientific's ImmunoCap ISAC (Immuno Solid-phase Allergen Chip) system, a multiplexed array that determines reactivities to 11 citrullinated peptides, we analysed serum/plasma of 195 healthy controls and 1282 early @entity625 @entity1 from two independent cohorts: the Leiden Early Arthritis Clinic (n   =   1013) and the IMPROVED (n   =   269) cohort. Findings were compared with results primarily of the anti-citrullinated cyclic peptide 2 (anti- @entity14965 ) assay but also with anti- @entity16837 and anti-mutated citrullinated @entity2277 (anti-MCV) assays. The associations between @entity7134 reactivities and @entity1 characteristics, risk factors (shared epitope, smoking) and disease outcomes (progression of undifferentiated @entity625 to @entity309 ( @entity309 ) and severity of @entity2720 ) were assessed. RESULTS: Thirty-one percent of anti- @entity14965 -negative @entity309 @entity1 displayed reactivity toward citrullinated peptides in the multiplex assay. These @entity1 had a positive signal toward a more restricted peptide repertoire than anti- @entity14965 -positive @entity309 @entity1 (median of 1 versus 5). Within anti- @entity14965 -negative @entity1 , @entity7134 reactivity as detected by multiplex array was not significantly associated with known risk factors or clinical or prognostic parameters. The frequency of sera from anti- @entity14965 -negative @entity309 @entity1 who were positive for the multiplexed peptides was comparable to the frequency in non- @entity309 arthritic @entity1 (27  %). CONCLUSIONS: Additive citrulline peptide reactivities detected by the current multiplex system did not reach significant power to be @entity309 -specific. The presence of residual @entity7792 reactivities detected by this multiplex system in @entity625 @entity1 who are negative in commercial @entity7134 assays needs to be interpreted with caution.

An investigation of the added value of an XXXX multiplex assay in an early @entity309 setting.

@entity1 :: ('9606', 'Species') :: ['patients', 'patient'] @entity16837 :: ('340351', 'Gene') :: ['CCP-3'] @entity7792 :: ('CHEBI:16349', 'Chemical') :: ['citrulline'] @entity625 :: ('MESH:D001168', 'Disease') :: ['arthritis'] @entity14965 :: ('79841', 'Gene') :: ['CCP-2'] @entity2277 :: ('7431', 'Gene') :: ['vimentin'] @entity2720 :: ('MESH:D007592', 'Disease') :: ['joint destruction'] @entity7134 :: ('5657', 'Gene') :: ['ACPA'] @entity309 :: ('MESH:D001172', 'Disease') :: ['rheumatoid arthritis', 'RA']
@entity7134 :: (5657,Gene) :: ['ACPA']
