Antigen-specific HLA-DR activation marker on functional T-cells associated with progressive non-tuberculous mycobacterial lung disease (NTM-LD)

<bold>Background:</bold> Clinical prediction of progressive NTM-LD remains challenging, and accurate immune biomarkers to determine disease progression are needed. We hypothesize flow cytometric (FC) detection of T-cell markers after ex vivo antigen challenge in peripheral blood mononuclear cells (PBMCs) with mycobacterial antigens can differentiate patients with progressive vs. non-progressive NTM-LD. <bold>Aim and objective:</bold> To determine if a multiparameter immunoprofiling with HLA-DR T-cell activation markers can differentiate patients with progressive vs. non-progressive NTM-LD. <bold>Methods:</bold> Fourty-three NTM-LD patients were studied, including 23 non-progressive and 20 progressive NTM-LD based on radiological and clinical evaluations. PBMCs were isolated and stimulated with PPD, MTB300, RD1-peptides and control antigens. We evaluated the diagnostic utility of CD4 and CD8 T-cell activation markers by ROC and non-parametric statistics. <bold>Results:</bold> Patients with progressive NTM-LD showed a statistically significant higher frequency of antigen-specific CD3+CD8+ IFN-γ+HLA-DR+ and CD3+CD4+TNF-α+HLA-DR+ subsets when compared to non-progressors. PPD-specific CD8+IFN-γ+HLA-DR+ showed 65% (95%CI: 38-78) sensitivity and 74% (95%CI: 63-93) specificity with an area under the curve (AUC) of 0.74. RD1-specific stimulated CD4+TNF-α+HLA-DR+ showed 50% (95% CI: 30-70) sensitivity and 83% (95% CI: 63-93) specificity with an AUC = 0.68. <bold>Conclusion:</bold> Our study findings suggest that antigen-specific IFN-γ+ and TNF-α+ HLA-DR+ T-cells can be useful biomarkers to differentiate progressive and non-progressive NTM-LD patients.