Study on myeloperoxidase role in antituberculous defense in the context of cytokine activation.

Myeloperoxidase (MPO), next to the NO synthase2 (NOS2), and NADPH oxidase, is the key enzyme of the oxidative burst responsible for the antimicrobial immunity. Because MPO participates in the eradication of Mycobacterium tuberculosis in the in vitro model and the extracellular enzyme may activate cells to cytokine synthesis, we investigated the changes in the enzyme concentration in serum of patients with active pulmonary tuberculosis (TB) and correlations between MPO and TNF-alpha, IFN-gamma, and IL-12. To our knowledge, our study is the first to indicate the involvement of MPO during active TB which manifested itself in the significant increase in serum concentration. The statistically significant elevation of TNF-alpha and IL-12 was also noticed in serum of the TB positive group. The statistical analysis revealed no correlation between the cytokine and MPO production in the studied cases. However, the increase in TNF-alpha and IL-12 serum concentration with simultaneous elevation of serum MPO in the group of the highest enzyme concentration may imply that correlation between the enzyme and the cytokines should not be excluded. Our study suggests possible involvement of MPO in the antituberculous, immunological response, and implies its connection with TNF-alpha and IL-12 activation.