Increased Th1 cells with disease resolution of active pulmonary tuberculosis in non-atopic patients

Type 1 CD4⁺ T helper (Th1) cells mediate resistance to Mycobacterium tuberculosis (Mtb), and Th2 immunity generates specific immunoglobulin E upon allergen exposure. We investigated the impact of active tuberculosis (TB), atopic status, and anti-TB treatment on the balance between Th1 and Th2 (type 2 CD4⁺ T helper) immunity. CD4⁺ /interferon (IFN)-γ⁺ Th1 cells (%Th1) and CD4⁺ /interleukin-4⁺ Th2 cells (%Th2) in bronchoalveolar lavage (BAL) fluid and peripheral blood mononuclear cells (PBMCs) were measured by flow cytometry. The BAL %Th1 was higher in TB patients at baseline, compared to that in non-TB subjects, and was further increased in TB patients after stimulation with phorbol myristate acetate and ionomycin. The stimulated BAL %Th1 was inversely correlated with the severity score of chest radiography in TB patients. Heat-killed Mtb triggered more IFN-γ and nitrite production, as determined by enzyme-linked immunosorbent assay and the Griess reaction, respectively, from the alveolar macrophages of TB patients than that of non-TB subjects. Non-atopic TB participants had a higher %Th1 in PBMCs, compared to atopic individuals, and their %Th1 decreased after 3-month anti-TB treatment. Th1 response is provoked by active TB infection, is associated with less severe radiographic changes, is reduced in atopic patients with active TB infection, and is attenuated after anti-TB treatment.