Natural killer cell cytotoxic factor (NKCF), a cytotoxic factor contributing to human natural killer cell-mediated cytotoxicity, was generated from lymphocyte-conditioned medium using various stimuli. Crude NKCF activity was concentrated, and partially purified by ammonium sulfate precipitation and gel filtration. NKCF activities eluted as two molecular weight peaks, corresponding to Mr 33,000-...

The study by Souza-Fonseca-Guimaraes and colleagues in the previous issue of Critical Care shows several alterations in blood natural killer (NK) characteristics during human sepsis and systemic inflammatory response syndrome, including changes in NK cell numbers, Toll-like receptor (TLR) expression, and responsiveness to TLR agonists. This paper advances our knowledge of NK cell biology during...

Chicken natural killer (NK) cells are not well defined, so little is known about the molecular interactions controlling their activity. At day 14 of embryonic development, chick spleens are a rich source of T-cell-free CD8αα(+), CD3(-) cells with natural killing activity. Cell-mediated cytotoxicity assays revealed complex NK cell discrimination of MHC class I, suggesting the presence of multipl...

Introduction Metastatic rhabdomyosarcoma (RMS) is a challenging tumor entity that evades conventional treatments and endogenous antitumor immune responses, highlighting the need for novel therapeutic strategies. Applying chimeric antigen receptor (CAR) technology to natural killer (NK) cells may offer safe, effective, affordable therapies enhance cancer surveillance. Methods Here, we assess eff...

To determine the role of natural killer (NK) cells in the regulation of human erythropoiesis, we studied the effects of NK-enriched cell populations on the in vitro proliferation of erythroid stem cells at three different levels of maturation (day 14 blood BFU-E, day 5-6 marrow CFU-E, and day 10-12 marrow BFU-E). NK cells were enriched from blood by Percoll density gradient centrifugation and b...

Cancer vaccines used to generate specific cytotoxic T lymphocytes are not effective against tumor cells that have lost or suppressed expression of their class I major histocompatibility complex proteins. This loss is common in some cancers and particularly in metastatic lesions. We show that beta2-microglobulin-deficient class I-negative melanoma variants derived from patients undergoing specif...

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 critical immune effector cells in the fight against cancer. As NK cells in cancer patients are highly dysfunctional and reduced in number, adoptive transfer of large numbers of cytolytic NK cells and their potential to induce relevant antitumor responses are widely explored in cancer immunotherapy. Early studies from autologous NK cells have failed to demonstrate s...

One of the body's natural defense mechanisms against tumor cells is lysis of the invading cell by cytotoxic T-cells and natural killer (NK) cells. Five human hepatocellular carcinoma cell lines were found to have different sensitivities to killing by peripheral blood monocytes in a 51Cr release assay. This killing was demonstrated to be due to NK cell lysis. Electrical recording measurements of...

Natural-killer receptor group 2, member D (NKG2D) is a well characterized natural killer (NK) cell activating receptor that recognizes several ligands poorly expressed on healthy cells but up-regulated upon stressing stimuli in the context of cancer or viral infection. Although NKG2D ligands represent danger signals that render target cells more susceptible to NK cell lysis, accumulating eviden...