BACKGROUND Natural killer cells are an important component of the innate immune system. Anti-cancer therapies utilizing monoclonal antibodies also rely on the cytotoxicity of NK cells for their effectiveness. Here, we study the dynamics of NK cell cytotoxicity. METHODOLOGY/PRINCIPAL FINDINGS We observe that IL-2 activated human NK cells can serially hit multiple targets. Using functional assa...

Steroids have been shown to inhibit the function of fresh or IL-2-activated natural killer (NK) cells. Since IL-15 plays a key role in NK-cell development and function, we comparatively analyzed the effects of methylprednisolone on IL-2- or IL-15-cultured NK cells. Methylprednisolone inhibited the surface expression of the major activating receptors NKp30 and NKp44 in both conditions, whereas N...

Human NK cells can be activated by a variety of different cell surface receptors. Members of the SLAM-related receptors (SRR) are important modulators of NK cell activity. One interesting feature of the SRR is their homophilic interaction, combining receptor and ligand in the same molecule. Therefore, SRR cannot only function as activating NK cell receptors, but also as activating NK cell ligan...

The assessment of the biological activity of capsaicin, the compound responsible for the spicy flavor of chili pepper, produced controversial results, showing either carcinogenicity or cancer prevention. The innate immune system plays a pivotal role in cancer pathology and prevention; yet, the effect of capsaicin on natural killer (NK) cells, which function in cancer surveillance, is unclear. T...

BACKGROUND Ischemia-reperfusion injury (IRI) significantly contributes to graft dysfunction after liver transplantation. Natural killer (NK) cells are crucial innate effector cells in the liver and express tumor necrosis factor-related apoptosis-inducing ligand (TRAIL), a potent inducer of hepatocyte cell death. Here, we investigated if TRAIL expression on NK cells contributes to hepatic IRI. ...

Natural killer (NK) cells are essential for killing transformed and virally infected cells. To prevent auto-reactivity, NK cell activation is inhibited by inhibitory receptors that activate the tyrosine phosphatase SHP-1, which dephosphorylates signaling molecules crucial for NK cell activation. Initially, only a single SHP-1 substrate was identified in NK cells, the GEF VAV1. We recently demon...

Natural killer (NK) cells are involved in innate immune responses to viral infections either via direct cytotoxicity which destroys virus-infected cells or production of immunoregulatory cytokines which modulate adaptive immunity and directly inhibit virus replication. These functions are mediated by different NK subpopulations, with cytotoxicity being generally performed by CD56(dim) NK cells,...

Peripheral blood lymphocytes from 14 adult male patients admitted to the hospital with complications of intravenous drug abuse (IDA) were examined for natural killer (NK) and antibody-dependent cellular cytotoxic (ADCC) activities, lectin-dependent cellular cytotoxicity, and interferon (IFN)- and interleukin 2 (IL-2)-induced NK activity. Serum was also assayed for circulating interferon levels ...

Natural killer (NK) cells serve as one of the first lines of defense against viral infections and transformed cells. NK cell cytotoxicity is not dependent on antigen presentation by target cells, but is dependent on integration of activating and inhibitory signals triggered by receptor-ligand interactions formed at a tight intercellular contact between the NK and target cell, i.e., the immune s...

We tested the effect of three different interferon-(IFN) inducing pyrimidinone molecules with cancer therapeutic potential on natural killer (NK) cells. Peritoneal exudate (PE) cells were selected for these studies because their NK cell cytotoxicity is very low. Augmentation of PE-NK cell cytotoxicity was observed in eight different strains of mice after i.p. administration of 250 mg/kg of each...