Reduced neutrophil granular proteins and post-treatment modulation in tuberculous lymphadenitis

BACKGROUND: Neutrophils are important for host innate immune defense and mediate inflammatory responses. Pulmonary tuberculosis (PTB) is associated with increased neutrophil granular protein (NGP) levels in the circulation. However, the systemic levels of neutrophil granular proteins were not examined in tuberculous lymphadenitis (TBL) disease. METHODS: We measured the systemic levels of NGP (myeloperoxidase [MPO], elastase and proteinase 3 [PRTN3]) in TBL and compared them to latent tuberculosis (LTB) and healthy control (HC) individuals. We also measured the pre-treatment (Pre-T) and post-treatment (Post-T) systemic levels of neutrophil granular proteins in TBL individuals upon anti-tuberculosis treatment (ATT) completion. In addition, we studied the correlation and discriminatory ability of NGPs using receiver operating characteristic (ROC) analysis. RESULTS: Our data suggests that systemic levels of NGPs (MPO, PRTN3, elastase) were significantly reduced in TBL individuals compared to LTB and HC individuals. Similarly, after ATT, the plasma levels of MPO and elastase but not PRTN3 were significantly elevated compared to pre-treatment levels. NGPs (except PRTN3) were positively correlated with absolute neutrophil count of TBL, LTB and HC individuals. Further, NGPs were able to significantly discriminate TBL from LTB and HC individuals. CONCLUSION: Hence, we conclude reduced neutrophil granular protein levels might be associated with disease pathogenesis in TBL.