Original approach for automated quantification of antinuclear autoantibodies by indirect immunofluorescence.
BACKGROUND
Indirect immunofluorescence (IIF) is the gold standard method for the detection of antinuclear antibodies (ANA) which are essential markers for the diagnosis of systemic autoimmune rheumatic diseases. For the discrimination of positive and negative samples, we propose here an original approach named Immunofluorescence for Computed Antinuclear antibody Rational Evaluation (ICARE) based on the calculation of a fluorescence index (FI).


METHODS
We made comparison between FI and visual evaluations on 237 consecutive samples and on a cohort of 25 patients with SLE.


RESULTS
We obtained very good technical performance of FI (95% sensitivity, 98% specificity, and a kappa of 0.92), even in a subgroup of weakly positive samples. A significant correlation between quantification of FI and IIF ANA titers was found (Spearman's ρ = 0.80, P < 0.0001). Clinical performance of ICARE was validated on a cohort of patients with SLE corroborating the fact that FI could represent an attractive alternative for the evaluation of antibody titer.


CONCLUSIONS
Our results represent a major step for automated quantification of IIF ANA, opening attractive perspectives such as rapid sample screening and laboratory standardization.
Aix-Marseille Université, Laboratoire d'Immunologie, Pôle de Biologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, 147 boulevard Baille, 13005 Marseille, France.
Daniel
D
Bertin
Aix-Marseille Université, Centre de Néphrologie et Transplantation Rénale, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, 13005 Marseille, France.
Noémie
N
Jourde-Chiche
Aix-Marseille Université, Laboratoire d'Immunologie, Pôle de Biologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, 147 boulevard Baille, 13005 Marseille, France ; Aix-Marseille Université, UMR INSERM 1067 & UMR CNRS 7333, Laboratoire "Adhésion et Inflammation," 13288 Marseille Cedex 09, France.
Pierre
P
Bongrand
Aix-Marseille Université, Laboratoire d'Immunologie, Pôle de Biologie, Hôpital de la Conception, Assistance Publique-Hôpitaux de Marseille, 147 boulevard Baille, 13005 Marseille, France ; Aix-Marseille Université, INSERM UMR 1076, Laboratoire "Endothélium, Pathologies Vasculaires et Cibles Thérapeutiques," Faculté de Pharmacie, 13385 Marseille Cedex 05, Marseille, France.
Nathalie
N
Bardin
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D000974:Antibodies, Antinuclear / Q000276:immunology; D001327:Autoimmune Diseases / Q000175:diagnosis / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods* / Q000592:standards; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012016:Reference Values; D015203:Reproducibility of Results; D055815:Young Adult
D000974:Antibodies, Antinuclear