Cox, Thomas

Abstract Background Biomarkers that predict the patients most likely to develop progressive NTM-LD are urgently needed. We hypothesize flow cytometric (FC) detection of T cell markers after ex vivo antigen challenge in PBMC can differentiate patients with progressive vs. nonprogressive NTM-LD. We also measured the serum anti-glycopeptidolipid core IgA antibody by commercial ELISA kit and compared with FC immunoprofiling results. Methods PBMCs were isolated from patients with NTM-LD and stimulated with purified protein derivative (PPD), mycobacteria-specific peptide pools (MTB300, RD1-peptides). We have performed ELISA and FC T-cell phenotypic assays to measure diagnostic accuracy of these assays by ROC and non-parametric statistics analysis. Results A total of 29 NTM-LD patients were studied and classified into 15 non-progressive and 14 progressive NTM-LD based on radiological and clinical evaluation. Patients with progressive NTM-LD showed a statistically significantly higher frequency of PPD-specific CD3+/CD8+ IFN-γ+HLA-DR+ subsets and high diagnostic accuracy compared with non-progressors: Sensitivity = 80% specificity = 71.4% with the ROC of 0.72. There were no other statistically significant differences in other antigen-stimulated T-cell subsets but a trend was observed with HLA-DR+TNF-α+, CD25+CD134+ and CD25+PDL1+ T-cell subsets in progressors. The anti-GPL IgA levels did not show a significant difference and might not be useful in distinguishing progressive from non-progressive NTM-LD. Conclusion Our study findings suggest that PPD-specific CD8+ IFN-γ+HLA-DR+ can distinguish progressive and nonprogressive NTM-LD patients, which can identify those patients at risk of disease progression.