title: Activin-A attenuates several human natural killer cell functions.
abstract: Dendritic-cell (DC) and natural killer (NK)-cell interactions are critical in sculpting the adaptive immune response. However, the mechanisms by which DCs down-regulate NK-cell functions are not well understood. NK-cell function is inhibited by transforming growth factor beta (TGF-beta), but DCs do not appear to produce TGF-beta. We have previously shown that activated human DCs produce large amounts of activin-A, a TGF-beta superfamily member, which autoregulates DC function. The present report shows that NK-cells express type I and II activin receptors and that activin-A triggers NK-cell Smad 2/3 signaling. Furthermore, activin-A directly regulates NK cell functions by (1) down-regulating the T-box transcription factor T-bet and interferon gamma (IFN-gamma) but not perforin or granzyme mRNA; (2) suppressing NK-cell IFN-gamma production as potently as TGF-beta; and (3) suppressing NK-cell CD25 expression and proliferation and sculpting NK-cell cytokine and chemokine profiles. Interestingly, unlike TGF-beta, activin-A weakly down-regulates the NK-cell natural cytotoxicity receptors (NCRs) NKp30 and NKG2D but does not attenuate their cytotoxic function. These findings provide the first evidence for a novel immune regulatory role of activin-A during DC-mediated NK-cell regulation, highlighting the potential of antagonizing activin-A signaling in vivo to enhance NK cell-mediated immune functions and adaptive immunity.
authors.affiliation: Ludwig Institute for Cancer Research, Melbourne Centre for Clinical Sciences, Austin Health, Heidelberg, Australia. neil.robson@ludwig.edu.au
authors.forename: Neil C
authors.initials: NC
authors.lastname: Robson
authors.forename: Heng
authors.initials: H
authors.lastname: Wei
authors.forename: Tristan
authors.initials: T
authors.lastname: McAlpine
authors.forename: Naomi
authors.initials: N
authors.lastname: Kirkpatrick
authors.forename: Jonathan
authors.initials: J
authors.lastname: Cebon
authors.forename: Eugene
authors.initials: E
authors.lastname: Maraskovsky
mesh_terms: D028341:Activins / Q000378:metabolism / Q000494:pharmacology / Q000502:physiology*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D003602:Cytotoxicity, Immunologic / Q000187:drug effects; D003713:Dendritic Cells / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007108:Immune Tolerance / Q000187:drug effects; D007371:Interferon-gamma / Q000378:metabolism; D019169:Jurkat Cells; D020014:K562 Cells; D007694:Killer Cells, Natural / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D018125:Receptors, Transforming Growth Factor beta / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics; D051785:Smad Proteins / Q000378:metabolism / Q000502:physiology
chemical_list: D018125:Receptors, Transforming Growth Factor beta; D051785:Smad Proteins; C422405:activin A; D028341:Activins; D007371:Interferon-gamma