Enhanced expression of TNF-α type-1 receptors by immune cells in active pulmonary tuberculosis.

Background: Tumour necrosis factor-alpha (TNF-α) and its inhibitors are involved in both defence against tuberculosis (TB) and damage to the host by TB. Notably, the change in receptor expression on cell density is a key mechanism in regulation of the biological properties of cytokines.

Objective: To study the differences in TNF-α receptor (TNFR) expression in patients with active pulmonary tuberculosis (aPTB) in correlation with the parameters of disease severity.

Methods: TNFR1/2 levels on peripheral blood mononuclear cells (PBMCs) from 45 patients with aPTB and 150 healthy controls were analysed by flow cytometry using monoclonal antibodies and QuantiBRITE beads. Soluble TNFR1/2 and TNF-α in serum were measured using an enzyme-linked immunosorbent assay.

Results: TNFR1 expression in aPTB patients was increased in the main populations of immune cells. Patients who were Mycobacterium tuberculosis culture-positive on bronchoscopy had higher levels of the soluble forms of TNFR1 (sTNFR1) than M. tuberculosis-negative patients.

Conclusion: Active TB was shown to cause activation of different immune cell types by increasing TNFR1 expression on cells and reducing sTNFR1 expression compared with healthy controls. M. tuberculosis-positive patients with disseminated infection had the highest sTNFR1 serum level compared with other patients, but did not differ in receptor expression on PBMCs.