Department of Microbiology and Physiological Systems
Bacteria | Bacterial Infections and Mycoses | Immunopathology | Pathogenic Microbiology
Invariant natural killer T (iNKT) cells are activated during infection, but how they limit microbial growth is unknown in most cases. We investigated how iNKT cells suppress intracellular Mycobacterium tuberculosis (Mtb) replication. When co-cultured with infected macrophages, iNKT cell activation, as measured by CD25 upregulation and IFNgamma production, was primarily driven by IL-12 and IL-18. In contrast, iNKT cell control of Mtb growth was CD1d-dependent, and did not require IL-12, IL-18, or IFNgamma. This demonstrated that conventional activation markers did not correlate with iNKT cell effector function during Mtb infection. iNKT cell control of Mtb replication was also independent of TNF and cell-mediated cytotoxicity. By dissociating cytokine-driven activation and CD1d-restricted effector function, we uncovered a novel mediator of iNKT cell antimicrobial activity: GM-CSF. iNKT cells produced GM-CSF in vitro and in vivo in a CD1d-dependent manner during Mtb infection, and GM-CSF was both necessary and sufficient to control Mtb growth. Here, we have identified GM-CSF production as a novel iNKT cell antimicrobial effector function and uncovered a potential role for GM-CSF in T cell immunity against Mtb.
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Citation: PLoS Pathog. 2014 Jan;10(1):e1003805. doi: 10.1371/journal.ppat.1003805. Link to article on publisher's site
Rothchild, Alissa C.; Jayaraman, Pushpa; Nunes-Alves, Claudio; and Behar, Samuel M., "iNKT cell production of GM-CSF controls Mycobacterium tuberculosis" (2014). University of Massachusetts Medical School Faculty Publications. 441.
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