Homeostasis of subpopulations Th17- and Treg-lymphocytes plays an important role in a holistic and coordinated process of eradication of pathogens and preventing the spread of infection in the body. Study of molecular mechanisms controlling the balance of these cells in the formation of immune deviation in the pathogenesis of infection are particularly relevant. The article presents the results of a study of mRNA expression of transcription factors Th17- and Treg-lymphocytes--RORC2 and FoxP3, respectively, as well as the presence of these cells in peripheral blood in infectious disease (based on an example of infection caused by Mycobacterium tuberculosis). It was established that during the infiltrative (regardless of drug susceptibility testing) and disseminated drug-susceptible pulmonary tuberculosis accompanied by Th17-polarized differentiation of T-lymphocytes, as evidenced by the increased number of CD4+CD161+IL17A+ cells in the blood in association with increased mRNA expression of the transcription factor RORC2 in lymphocytes. In disseminated drug-resistant pulmonary tuberculosis T-lymphocyte differentiation is carried out mainly in the direction of immunosuppressive Treg-cells, as evidenced by the increase in their number in the blood in association with elevated levels of mRNA expression of the transcription factor FoxP3 in lymphocytes.