= 10 for CMV; = 5 for EBV; *, P < 0.05. Our results demonstrate that a couple of hours of sleep loss suffice to reduce the adhesion capacity of antigen-specific T cells. execution SBC-115076 of efficient T cell responses require the recruitment of T cells to lymphoid and nonlymphoid tissues (Ley et al., 2007), as well as the formation of immunological synapses with antigen-presenting cells (APCs) or target cells (such as virus-infected or malignancy cells; Scholer et al., 2008; Dustin and Long, 2010; Fooksman et al., 2010). The modulation of T cell adhesiveness by regulation of integrin activation is crucial to these actions. Recirculating T lymphocytes express high levels of membrane-bound 2-integrins (Dimitrov et al., 2009, 2010), which are maintained in a nonadhesive (inactive) state (Evans et al., 2009). Immediate activation (i.e., increase in affinity and avidity) of 2-integrins induced by chemokines allows the arrest of T cells around the endothelium and their subsequent extravasation into tissues (Ley et al., 2007). A similar activation of 2-integrins in response to TCR engagement by cognate peptides offered by MHC molecules (pMHC) on APCs or target cells is also required for the formation of stable immunological synapses (Dustin and Springer, 1989; Dustin and Long, 2010; Fooksman et al., 2010; Long, 2011). Research around the regulation of integrin-mediated adhesion has focused over the past 35 yr exclusively on pro-adhesive signals, such as chemokines and pMHC. Only recently, the presence of anti-adhesive factors, such as Gs (a heterotrimeric G protein subunit that activates the cAMP-dependent pathway)-coupled receptor agonists, nitric oxide, and carbon monoxide has become obvious (Chigaev et al., 2008, 2011a,b, 2014). Specifically, it has been shown in monocytes that this chemokine-induced integrin affinity is usually down-regulated by anti-adhesive signaling derived from Gs-coupled receptor agonists like amthamine (H2-histaminergic receptor agonist) and isoproterenol (1/2-adrenergic receptor [AR] agonist; Chigaev et al., 2008, SBC-115076 2011b). The recruitment of cytotoxic leukocytes to the blood during daytime and acute physical or psychological stress has been suggested to be mediated by epinephrine (a 1/2-AR agonist), which induces a down-regulation of integrins, resulting in the de-adhesion of the cells from your endothelium of the marginal pool (Dimitrov et al., 2009, 2010). However, nothing is known about the effect of epinephrine or other Gs-coupled receptor agonists on TCR-mediated integrin activation and formation of immunological synapses. Several signaling molecules, including catecholamines (Wahle et al., 2005), prostaglandins (PGs; Scher and Pillinger, 2009; Kalinski, 2012), adenosine (Hoskin et al., 2008), dopamine (Yan et al., 2015), histamine, and serotonin (Kim et SBC-115076 al., 2013) exert anti-inflammatory IQGAP1 effects via their cognate Gs-coupled receptors. Given the common intracellular mediator cAMP, here we asked whether these substances also share anti-adhesive properties. Sleep is known as a condition characterized by low levels of endogenous Gs-coupled receptor agonists such as catecholamines (Dimitrov et al., 2015), PGs (Haack et al., 2009), and serotonin (Davies et al., 2014). We therefore additionally used sleep as an in vivo readout to assess effects of low levels of Gs-coupled receptor agonists on adhesive properties of antigen-specific T cells in a physiological condition. In addition, because of the strong circadian rhythm in the levels of catecholamines (Dimitrov et al., 2015), PGs (Kamperis et al., 2004), serotonin (Davies et al., 2014), and adenosine (Chagoya de Snchez et al., 1983), with a nadir during the rest phase, adhesion was measured across an entire day to detect a possible circadian rhythm of this parameter. For these purposes, we recruited healthy humans seropositive for CMV, because this chronic latent contamination is characterized by a high quantity of antigen-specific T cells, allowing for the analysis of different T cell subsets. Adhesive properties of the cells were assessed by a new circulation cytometryCbased assay using soluble pMHC multimers for staining and activation of the antigen-specific T cells, and fluorescent intercellular adhesion molecule (ICAM)C1 multimers (mICAM-1) for visualization of activated 2-integrins (Dimitrov et al., 2018). We show that catecholamines, PGE2, PGD2, and adenosine potently inhibit TCR-mediated integrin activation on human antigen-specific CD8+ T cells,.