Interferon-gamma Release Assay Results Are Reliable for Screening for Latent Tuberculosis in Antineutrophil Cytoplasmic Antibody-associated Vasculitis

Abstract

Background/aim: This study investigated a correlation between ex vivo interferon-gamma (IFN)-gamma production using IFN-gamma releasing assay (IGRA) and antineutrophil cytoplasmic antibody-associated vasculitis (AAV) activity assessed by Birmingham vasculitis activity score (BVAS) in AAV patients.

Patients and methods: A total of 113 patients with AAV were consecutively selected from the AAV cohort and their medical records were reviewed. IGRA was performed at AAV diagnosis and before the initiation of glucocorticoids or immunosuppressive drugs for AAV treatment.

Results: The median age was 61.8 years and 41.6% of the patients were men. Eighteen, 28, and 67 patients had EGPA, GPA, and MPA, respectively. Eighteen, 84, and 11 patients had positive, negative, and indeterminate results, and the median Nil, tuberculosis antigen, mitogen, and ex vivo IFN-gamma production were 0.1, 0.1, 10.0, and 9.8 IU/ml, respectively. There was no significant correlation between ex vivo IFN-gamma production and BVAS in AAV patients. When AAV patients were divided into two groups according to BVAS of 18, the higher tertile of BVAS, there was no significant difference in ex vivo IFN-gamma production between AAV patients with BVAS ≥18 and those without. In addition, there were no statistically significant correlations between ex vivo IFN-gamma production and BVAS in AAV patients with either indeterminate and negative IGRA results or only negative IGRA results.

Conclusion: There is no correlation between ex vivo IFN-gamma production and BVAS. This study provided information on the reliability of the IGRA results for latent tuberculosis screening in AAV patients regardless of the activity of AAV.