We showed that Il-6 gene transcription was upregulated in mouse lungs during the entire study period after intravenous injection with the strain H37Rv, in contrast to the transcription levels in mice injected with clinical strains: the strain 267/47 induced expression of this gene on the 30th day p.i.; the strain 120/26, on the 90th day p.i. It was reported previously that levels of IL-6 were higher in macrophages from TB patients than those from healthy persons [44]. The gene discussed is IL6; the disease is tuberculosis.