This study evaluates a diagnostic serological test for Non-Tuberculous Mycobacteria (NTM) infection in cystic fibrosis patients by measuring T cell response. It aims to highlight a dynamic response associated to the pathogen's presence. This multicenter case-control study involves two populations, providing a better understanding of the circulating T-IFNγ-MNT response in these patients.
Background: Evidence shows that Non-tuberculous Mycobacterial (NTM) infections have increased and are 1,000 to 8,000 times more frequent in patients with cystic fibrosis compared to the general population. The diagnosis is based on clinical, radiological, and microbiological criteria. Unfortunately, the first two criteria lack specificity, and microbiological detection of NTM is limited due to frequent sputum contamination by other pathogens in cystic fibrosis patients. Given these factors and the high incidence of NTM infections in this population, alternative diagnostic methods are necessary. Aim: This study aims to validate an innovative diagnostic test based on the IGRA (Interferon-Gamma Release Assay) method, which measures T lymphocyte response to Interferon gamma (IFNγ). The test will be conducted on a subset of patients selected from the CIMeNT cohort (ID-RCB: 2017-A00025-48). This cohort consists of cystic fibrosis patients whose NTM infection prevalence has been previously assessed. Method: This research is a multicenter case-control study. It includes two groups: a case group of patients with positive serological and/or microbiological responses indicating NTM infection, and a control group of patients without such responses. The test measures the host's immune response by evaluating circulating T cell activity. Specifically, it measures IFNγ release when T cells are in contact with NTM antigens. This method provides more informative diagnostics of NTM infection dynamics compared to serology or microbiology, which have known technical limitations. The study involves a single visit, which is part of the routine care for cystic fibrosis patients. During this visit, a routine blood draw will be performed and an additional 7 ml tube will be collected.
Study Type
OBSERVATIONAL
Enrollment
76
During the scheduled visit (V1), as part of routine care, a blood draw will be performed. On this occasion, an additional 7 ml tube will be collected to perform serology and culture. This will help define the group (NTM+ Cases/NTM- Controls) and measure cellular biomarkers.
CHU de Montpellier - Hôpital Arnaud de Villeneuve
Montpellier, France
RECRUITINGDetermination of interferon-gamma release assay
Evaluation of T lymphocyte activation following mycobacterial antigen stimulation. The level of interferon gamma (IFN-γ) released is the measured marker of this activation, quantified in IU/ml. Sensitivity and specificity pairs will be calculated for each threshold value of the IFNγ rate in the T cell response test. A Receiver Operating Characteristic (ROC) curve will be plotted with its Area Under the Curve (AUC) and 95% confidence interval. For each threshold, sensitivity and specificity values will be computed, along with their 95% confidence intervals. The assessment aims to diagnose NTM in patients, as confirmed by serology and/or positive culture.
Time frame: day 1 (V1)
Evaluation of T lymphocyte response
Measurement of IFN-γ release in response to T cell contact with NTM antigens, compared to clinical and radiological progression.
Time frame: day 1 (V1)
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