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Effects of beta-adrenergic receptor activation, cholera toxin and forskolin on human natural killer cell function.

ABSTRACT: Membranes from highly purified natural killer (NK) cells were ADP-ribosylated by treatment with cholera toxin (CTX). CTX resulted in a single band of specific 32P incorporation at Mr 43,600. CTX treatment of intact NK cells caused a 9-fold increase in cyclic AMP (cAMP) concentrations. Pretreatment of NK cells with CTX diminished their ability to lyse K562 tumour cells by up to 79%. Forskolin treatment elevated NK cell cAMP levels 8-fold and decreased lysis of K562 cells by up to 45%. Adrenaline and isoprenaline (isoproterenol) both inhibited lysis of K562 cells by approx. 35% and elevated cAMP by at least 2.5-fold, and their inhibition of lysis was reversed by propranolol. These data suggest that the stimulatory guanine-nucleotide-binding protein GS coupled to beta-adrenergic receptors is involved in transducing signals which inhibit NK cell lysis of tumour cells. CTX and forskolin also diminish the ability of NK cells to bind K562 cells (binding is necessary for lysis). This suggests that the NK-cell receptor(s) for the tumour cell may be altered as a consequence of cAMP-mediated events or by activation of GS.

SUBMITTER: Whalen MM

PROVIDER: S-EPMC1149703 | biostudies-other | 1990 Dec

REPOSITORIES: biostudies-other

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Project description:Recent reports suggest that Natural Killer (NK) cells may modulate pathogenesis of primary HIV-1 infection. However, HIV dysregulates NK-cell responses. We dissected this bi-directional relationship to understand how HIV impacts NK-cell responses during primary HIV-1 infection.Paired samples from 41 high-risk, initially HIV-uninfected CAPRISA004 participants were analysed prior to HIV acquisition, and during viraemic primary HIV-1 infection. At the time of sampling post-infection five women were seronegative, 11 women were serodiscordant, and 25 women were seropositive by HIV-1 rapid immunoassay. Flow cytometry was used to measure NK and T-cell activation, NK-cell receptor expression, cytotoxic and cytokine-secretory functions, and trafficking marker expression (CCR7, ?(4)?(7)). Non-parametric statistical tests were used. Both NK cells and T-cells were significantly activated following HIV acquisition (p?=?0.03 and p<0.0001, respectively), but correlation between NK-cell and T-cell activation was uncoupled following infection (pre-infection r?=?0.68;p<0.0001; post-infection, during primary infection r?=?0.074;p?=?0.09). Nonetheless, during primary infection NK-cell and T-cell activation correlated with HIV viral load (r?=?0.32'p?=?0.04 and r?=?0.35;p?=?0.02, respectively). The frequency of Killer Immunoglobulin-like Receptor-expressing (KIR(pos)) NK cells increased following HIV acquisition (p?=?0.006), and KIR(pos) NK cells were less activated than KIR(neg) NK cells amongst individuals sampled while seronegative or serodiscordant (p?=?0.001;p<0.0001 respectively). During HIV-1 infection, cytotoxic NK cell responses evaluated after IL-2 stimulation alone, or after co-culture with 721 cells, were impaired (p?=?0.006 and p?=?0.002, respectively). However, NK-cell IFN-y secretory function was not significantly altered. The frequency of CCR7+ NK cells was elevated during primary infection, particularly at early time-points (p<0.0001).Analyses of immune cells before and after HIV infection revealed an increase in both NK-cell activation and KIR expression, but reduced cytotoxicity during acute infection. The increase in frequency of NK cells able to traffic to lymph nodes following HIV infection suggests that these cells may play a role in events in secondary lymphoid tissue.

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Effects of beta-adrenergic receptor activation, cholera toxin and forskolin on human natural killer cell function.

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