Aim. To assess external respiration (ER) and its relationship with the activity of enzymes involved in purine metabolism in patients with acute and chronic forms of pulmonary tuberculosis (TB).Materials and methods. In patients with acute and chronic TB, we assessed the activity of adenosine deaminase (ADA)-1, 2 in the blood serum (eADA), mononuclear cells, and neutrophils, the concentration of ecto-5’-nucleotidase (eNT5E) in the blood serum, the level of CD26 (dipeptidyl peptidase-4, DPPIV) in the blood serum and mononuclear cells, production of reactive oxygen intermediates (ROI) and reactive nitrogen intermediates (RNI) in mononuclear cells and neutrophils, as well as parameters of ER.Results. Patients with TB were found to have an increase in the concentration of eNT5E and eADA-2 activity in the blood serum, stimulated production of ROI in neutrophils, a decrease in the concentration of DPPIV (CD26) in mononuclear cells, and a fall in the production of RNI in mononuclear cells and neutrophils. In patients with chronic TB, a decrease in the activity of ADA-1 in mononuclear cells and a fall in the concentration of DPPIV (CD26) in the blood serum were noted. In patients with acute TB, a decrease in the activity of eADA-1 in the blood serum and ADA-1 in neutrophils, reduced production of ROI in mononuclear cells, and an increase in spontaneous production of ROI in neutrophils were revealed. Correlations were found between the parameters of ER and the concentration of eNT5E in the blood serum, spontaneous production of ROI in mononuclear cells and production of RNI in neutrophils in chronic TB, as well as between eADA-2 in the blood serum, ADA-1 in neutrophils, DPPIV (CD26) activity in mononuclear cells, and ROI and RNI production in mononuclear cells and neutrophils.Conclusion. The data obtained make it possible to associate regulation of external respiration with parameters of purine metabolism, in particular with the concentration and activity of enzymes responsible for generation and metabolism of adenosine, that determine its level outside cells and inside mononuclear cells and neutrophils, with expression of cofactor molecules, as well as with the duration of activation of cells in innate immunity, neutrophils, and monocytes/ macrophages, determined largely by the potential of adenosine regulation.