Diminished systemic levels of antimicrobial peptides in tuberculous lymphadenitis and their reversal after anti-tuberculosis treatment

Pulmonary tuberculosis is associated with higher plasma levels of antimicrobial peptides (AMPs) and lower granulysin levels. However, the association of AMPs with tuberculous lymphadenitis (TBL) is not well studied. Hence, we measured the plasma levels of human beta defensin-2 (HBD2), granulysin, human neutrophil peptides 1-3 (HNP1-3) and cathelicidin (LL37) in TBL compared to latent tuberculosis (LTB) and healthy controls (HC) and in TBL individuals upon completion of anti-tuberculosis treatment (ATT). We examined the association of AMPs with TBL lymph node culture grade or lymph node involvement. Finally, the discriminatory potential of these proteins was assessed using receiver operating characteristic (ROC) analysis. TBL individuals display significantly diminished circulating levels of AMPs (granulysin and HNP1-3) but not HBD-2 and LL-37 in comparison to LTB and HCs. Similarly, after ATT, both HBD-2 and HNP1-3 were significantly elevated and LL-37 was significantly reduced in TBL individuals. Granulysin and HNP1-3 discriminates TBL from LTB and HC individuals upon ROC analysis. AMPs did not exhibit significant correlation either with lymph node culture grades or lymph node involvement. Overall, TBL individuals show decreased AMPs and their reversal after ATT suggesting their association with underlying immune alteration in this poorly studied form of TB disease.