Article
Live and Inactivated Influenza Vaccines Induce Similar Humoral Responses, but Only Live Vaccines Induce Diverse T-Cell Responses in Young Children
The Journal of Infectious Diseases
(2011)
Abstract
Human γ(9)δ(2) T cells potently inhibit pathogenic microbes, including intracellular mycobacteria, but the key inhibitory mechanism(s) involved have not been identified. We report a novel mechanism involving the inhibition of intracellular mycobacteria by soluble granzyme A. γ(9)δ(2) T cells produced soluble factors that could pass through 0.45 µm membranes and inhibit intracellular mycobacteria in human monocytes cultured below transwell inserts. Neutralization of TNF-α in co-cultures of infected monocytes and γ(9)δ(2) T cells prevented inhibition, suggesting that TNF-α was the critical inhibitory factor produced by γ(9)δ(2) T cells. However, only siRNA- mediated knockdown of TNF-α in infected monocytes, but not in γ(9)δ(2) T cells, prevented mycobacterial growth inhibition. Investigations of other soluble factors produced by γ(9)δ(2) T cells identified a highly significant correlation between the levels of granzyme A produced and intracellular mycobacterial growth inhibition. Furthermore, purified granzyme A alone induced inhibition of intracellular mycobacteria, while knockdown of granzyme A in γ(9)δ(2) T cell clones blocked their inhibitory effects. The inhibitory mechanism was independent of autophagy, apoptosis, nitric oxide production, type I interferons, Fas/FasL and perforin. These results demonstrate a novel microbial defense mechanism involving granzyme A-mediated triggering of TNF-α production by monocytes leading to intracellular mycobacterial growth suppression. This pathway may provide a protective mechanism relevant for the development of new vaccines and/or immunotherapies for macrophage-resident chronic microbial infections.
Disciplines
Publication Date
September 15, 2011
DOI
10.1093/INFDIS/JIR436
Citation Information
Hoft DF, Babusis E, Worku S, Spencer CT, Lottenbach K, Truscott SM, Abate G, Sakala IG, Edwards KM, Creech CB, Gerber MA, Bernstein DI, Newman F, Graham I, Anderson EL, Belshe RB. Live and inactivated influenza vaccines induce similar humoral responses, but only live vaccines induce diverse T-cell responses in young children. J Infect Dis. 2011 Sep 15;204(6):845-53. doi: 10.1093/infdis/jir436. Epub 2011 Aug 15. PMID: 21846636; PMCID: PMC3156924.