Open Access

ORIGINAL ARTICLE

Assessment of an ultra-sensitive IFNγ immunoassay prototype for latent tuberculosis diagnosis

Elyes Ben Salah¹, Karim Dorgham¹, Mylène Lesénéchal², Camille Pease², Laure Allard², Céline Dragonetti², Guy Gorochov¹, Amélie Guihot¹, Delphine Sterlin¹

1 Sorbonne université, Inserm, Centre d’immunologie et des maladies infectieuses (CIMI-Paris), AP-HP, groupement hospitalier de la Pitié-Salpêtrière, département d’immunologie, 75013 Paris, France
2 bioMérieux, R&D Immunoassays, chemin de l’Orme, 69280 Marcy-l’Étoile, France

* Corresponding Author: Sorbonne université,

European Cytokine Network 2018, 29(4), 136-145. https://doi.org/10.1684/ecn.2018.0417

Accepted 11 October 2018;

Abstract

Worldwide there are about 1.7 billion individuals with latent tuberculosis infection (LTBI) and only 5% to 15% will develop active tuberculosis (TB). It is recommended to treat only those most at risk of develop ing active TB to avoid problems of drug resistance. LTBI diagnosis involves reviewing the individual’s medical history, physical examination, and biological tests. Interferon gamma release assays (IGRA) can yield “undetermi nate” or “uncertain” results, which makes clinical management decisions difficult. We assessed an ultra-sensitive immunoassay prototype based on single molecule array (SiMoA) technology to evaluate its overall performance, and in particular, its performance for indeterminate and uncertain positive or negative samples, as classified by the results from the current ELISA technique used for IFN quantification. We analyzed samples from hospitalized or consulting patients and healthcare workers from three hospitals in Paris, previously classified as negative (n=30), positive (n=35), uncertain negative (n=25), uncertain positive (n=31), or indeterminate (n=30). We observed that with the SiMoAassay83.3%oftheindeterminatesamplesbecameinterpretable and could be classified as negative, whereas 74%ofuncertainpositive samples were classified as positive. Most uncertain negative samples (72%) were reclassified as uncertain positive (68%) or positive (4%). The results suggest that the ultra-sensitive SiMoA IFN assay could represent a useful tool for the identification of true positive and negative samples among those giving indeterminate or uncertain results with the TB IGRA assay currently used.

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