title: Mechanism of norepinephrine-mediated inhibition of human NK cytotoxic functions: inhibition of cytokine secretion, target binding, and programming for cytotoxicity.
abstract: Norepinephrine (NE) has been shown to inhibit human peripheral blood-derived natural-killer (NK) cell cytotoxicity (NKCC) in vitro. We demonstrate in this study that NE not only inhibits IL-2-activated NKCC but antibody-dependent cellular cytotoxicity (ADCC) as well. NK cytotoxicity by purified NK cells against K562 (NKCC) and against Raji cells (ADCC) were inhibited by NE (1-100 microM) by more than 50% in a 4-h (51)Cr release assay. The mechanism underlying the inhibition has been examined. NK cytotoxicity is dependent on target recognition and formation of NK-target conjugates, and activation by IL-2 is dependent on the secretion of cytokines (such as TNF-alpha) by NK cells. We hypothesized that the inhibition of NK functions by NE may be due to disruption of NK-target conjugation, blocking programming for lysis, and/or inhibition of cytokine secretion. Pretreatment of human peripheral blood mononuclear cells (PBMC) with NE for 15 min significantly reduced the binding to K562 cells by CD16(+) NK lymphocytes. In the presence of K562 cells, NE down-regulated the expression of CD16 (FcgammaRIII) by human PBMC, an NK cell receptor responsible and necessary for ADCC and cytokine secretion. We also demonstrate that NE inhibited the IL-2-mediated up-regulation of the activation marker CD69. At concentrations of 10(-6) to 10(-5) M, NE inhibited TNF-alpha, IFN-gamma, and GM-CSF secretion by NK cells, which are essential for IL-2-driven NK maturation and functions. In addition, using single-cell analysis, NE pretreatment of lymphocytes reduced the frequency of killer cells in the NK-K562 conjugate population in a concentration-dependent manner, indicating an inhibition of the programming for lysis by NK cells. In summary, these data demonstrate that NE-induced inhibition of NK cytotoxicity is manifested at multiple levels, including a modification of NK cell receptor ligation to target cells, blockade of NK cytokine secretion necessary for NK maturation and differentiation, and inhibition of the target-induced activation of the cytotoxic mechanism(s) in NK cells. Thus, sympathetic activation, as often induced experimentally, may profoundly impair natural cellular immunity through varied measurable pathways.
authors: Department of Microbiology and Immunology, UCLA School of Medicine, 10833 Le Conte Avenue, Los Angeles, CA 90095, USA.
authors: Xiaohu
authors: X
authors: Gan
authors: Ling
authors: L
authors: Zhang
authors: George F
authors: GF
authors: Solomon
authors: Benjamin
authors: B
authors: Bonavida
mesh_terms: D015703:Antigens, CD / Q000378:metabolism; D000945:Antigens, Differentiation, T-Lymphocyte / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology; D002450:Cell Communication / Q000276:immunology; D002452:Cell Count; D003601:Cytotoxicity Tests, Immunologic; D015536:Down-Regulation / Q000187:drug effects / Q000276:immunology; D005434:Flow Cytometry; D006801:Humans; D007111:Immunity, Cellular / Q000187:drug effects / Q000276:immunology; D007376:Interleukin-2 / Q000494:pharmacology; D020014:K562 Cells / Q000166:cytology; D007694:Killer Cells, Natural / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D037181:Lectins, C-Type; D015213:Neuroimmunomodulation / Q000502:physiology; D009638:Norepinephrine / Q000494:pharmacology*; D017452:Receptors, IgG / Q000378:metabolism; D013566:Sympathomimetics / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D000099192:CD69 Antigens
chemical_list: D015703:Antigens, CD; D000945:Antigens, Differentiation, T-Lymphocyte; D000970:Antineoplastic Agents; D007376:Interleukin-2; D037181:Lectins, C-Type; D009638:Norepinephrine; D017452:Receptors, IgG; D013566:Sympathomimetics; D014409:Tumor Necrosis Factor-alpha; D000099192:CD69 Antigens