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FRI0268 Multifunctional Flow Cytometry Analysis of CD4+ T Cells as an Immune Biomarker for Latent Tuberculosis Status in Patients Treated with TNF Antagonists
  1. R. Scrivo1,
  2. I. Sauzullo2,
  3. F. Mengoni2,
  4. A. Ermocida2,
  5. V. Vullo2,
  6. C.M. Mastroianni2,3,
  7. G. Valesini1
  1. 1Department of Internal Medicine and Medical Specialties, Rheumatology Unit
  2. 2Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome
  3. 3Infectious Diseases Unit, Fondazione Eleonora Lorillard Spencer Cenci, Sapienza University of Rome, Latina, Italy

Abstract

Background No strategy has yet proved successful in monitoring tuberculosis (TB) infection during treatment with TNF antagonists. Even the new interferon-gamma (IFN-γ) release assays (IGRAs) produce dynamic changes in IFN-γ plasma levels with little correlation to clinical change. Recent studies show that multifunctional analysis of CD4+ T cells producing IFN-γ, IL-2, and TNF in response to M. tuberculosis-specific antigens may discriminate between active and latent TB infection (LTBI) and be superior to IGRAs in terms of TB detection.

Objectives To investigate the performance of multifunctional CD4+ T cells by intracellular cytokine flow cytometry assay in subjects with chronic inflammatory rheumatic diseases during long-term anti-TNF treatment.

Methods Before initiating biological therapy, patients underwent TB screening, also including QuantiFERON-TB Gold In-Tube (QFT-GIT), one of the IGRAs currently available. Patients with evidence of TB infection based on any of QFT-GIT, tuberculin skin test, chest radiograph results or other risk factors were considered affected by LTBI after excluding active TB. These subjects received a 9 month-course of isoniazid. QFT-GIT was serially repeated during biological therapy; after 36 months multifunctional analysis was also performed. Patients were classified into 3 groups based on their TB status before the onset of biological treatment and on IFN-γ level fluctuations evaluated by QFT-GIT during the follow-up: 12 patients with LTBI who showed IFN-γ level fluctuations; 11 patients with no evidence of LTBI at baseline showing IFN-γ level fluctuations and 10 patients with no evidence of LTBI at baseline and persistently negative IFN-γ levels.

Results No patient developed active TB during treatment with TNF antagonists. In LTBI subjects we observed a higher frequency of IFN-γ+ IL-2+ TNF+ CD4+ T cells compared to LTBI-negative patients showing IFN-γ level fluctuations (p=0.015), but no difference with respect to patients with no LTBI and persistently negative IFN-γ levels. The frequency of IFN-γ+ IL-2+ CD4+ T cells was significantly higher in LTBI patients compared to the other 2 groups of patients with no evidence of LTBI at baseline (p=0.006). Patients with no LTBI and persistently negative IFN-γ levels showed similar proportions of cells producing IFN-γ alone, IL-2 alone, and IL-2 in combination with TNF in response to M. tuberculosis-specific antigens.

Conclusions This is the first study evaluating multifunctional analysis of CD4+ T cells in patients treated with TNF antagonists, and suggests that it could be useful for ruling-out TB infection in patients classified at screening as LTBI-negative but who showed IGRA fluctuations under long-term TNF antagonist treatment. Despite LTBI patients were treated with isoniazid, their CD4+ T cells were found to produce multiple cytokines, unlike patients with no LTBI. Hence, multifunctional analysis may be a useful means of clarifying TB status when IFN-γ levels fluctuate with repeated IGRA testing, even in patients undergoing biological therapy.

Disclosure of Interest None declared

DOI 10.1136/annrheumdis-2014-eular.2520

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