This study evaluated T cell immune responses to purified protein derivative (PPD) and Mycobacterium tuberculosis (Mtb) in health care workers who remained free of active tuberculosis (HCWs w/o TB), health care workers who went on to develop active TB (HCWs w/TB), non-health care workers who were TB free (Non-HCWs) and tuberculosis patients presenting with minimal (Min TB) or advanced (Adv TB) disease. Peripheral blood mononuclear cells (PBMC) were stimulated with Mtb and PPD and the expression of T cell activation markers CD25+ and HLA-DR+, intracellular IL-4 and IFN-γ production and cytotoxic responses were evaluated. PBMC from HCWs who developed TB showed decreased percentages of cells expressing CD8+CD25+ in comparison to HCWs who remained healthy. HCWs who developed TB showed increased γδ TCR+ cell cytotoxicity and decreased CD3+γδ TCR- cell cytotoxicity in comparison to HCWs who remained healthy. PBMC from TB patients with advanced disease showed decreased percentages of CD25+CD4+ and CD25+CD8+ T cells that were associated with increased IL-4 production in CD8+ and γδ TCR+ phenotypes, in comparison with TB patients presenting minimal disease. TB patients with advanced disease showed increased γδ TCR+ cytotoxicity and reduced CD3+γδ TCR- cell cytotoxicity. Our results suggest that HCWs who developed TB show an early compensatory mechanism involving an increase in lytic responses of γδ TCR+ cells which did not prevent TB. © 2004 Federation of European Microbiological Societies. Published by Elsevier B.V. All rights reserved.
Ordway, D. J., Pinto, L., Costa, L., Martins, M., Leandro, C., Viveiros, M., … Dockrell, H. M. (2005). Gamma delta T cell responses associated with the development of tuberculosis in health care workers. FEMS Immunology and Medical Microbiology, 43(3), 339–350. https://doi.org/10.1016/j.femsim.2004.09.005