Experimental exposure of Burkholderia pseudomallei crude culture filtrate upregulates PD-1 on T lymphocytes

• Published in: Access microbiology 2020-05, Vol.2 (5), p.acmi000110-acmi000110
• Main Authors: Menon, Nivedita, Mariappan, Vanitha, Vellasamy, Kumutha M., Samudi, Chandramathi, See, Jia-Xiang, Ganesh, P. Sankar, Saeidi, Alireza, Vadivelu, Jamuna, Shankar, Esaki Muthu
• Format: Article
• Language: English
• ISSN: 2516-8290; 2516-8290
• DOI: 10.1099/acmi.0.000110

Burkholderia pseudomallei is the causative agent for melioidosis. Because of its intracellular nature, the bacterium is capable of replicating within a plethora of eukaryotic cell lines. B. pseudomallei can remain dormant within host cells without symptoms for years, causing recrudescent infections. Here, we investigated the pathogenesis mechanism behind the suppression of T cell responses by B. pseudomallei . Peripheral blood mononuclear cells (1×10 6  cells/well) isolated by Ficoll Paque (Sigma-Aldrich) density gradient centrifugation were incubated with optimized concentrations of bacterial crude culture filtrate antigens (CFAs) (10 ug ml −1 ) and heat-killed bacteria [1 : 10 multiplicity of infection (m.o.i.)]. Following incubation, cells were investigated for surface expression of coinhibitory molecules by flow cytometry. We found that B. pseudomallei induced the upregulation of programmed death 1 (PD-1), a molecule responsible for T cell exhaustion, on T cells in vitro following exposure to crude CFAs of B. pseudomallei . This upregulation of PD-1 probably contributes to poor immune surveillance and disease pathogenesis.