Bacterial endotoxin (lipopolysaccharide, LPS) and interleukin-2 (IL-2) are known to stimulate NK cell mediated cytotoxicity against tumor cells. In the present report we sought to correlate the stimulatory effect of LPS and IL-2 on NK cell activity with ultrastructural changes which occurred as a result of such stimulation. Peripheral blood mononuclear cells (PBMC) were purified from healthy do...

Natural killer (NK) cells are known to target cancer stem cells and undifferentiated tumors. In this paper, we provide a novel strategy for expanding large numbers of super-charged NK cells with significant potential to lyse and differentiate cancer stem cells and demonstrate the differences in the dynamics of NK cell expansion between healthy donors and cancer patients. Decline in cytotoxicity...

A t early times during viral infections, natural killer (NK) cells can contribute to direct antiviral defense (1, 2). The effect is most dramatic when they are stimulated to release the contents of their cytolytic granules for lysis of virus-infected target cells. Type 1 interferons (IFNs), produced during innate responses to infections, induce elevated NK cell cytotoxicity. Killing, however, i...

A total of 50 lung cancer (CA) patients and 20 normal persons as controls were included in our study. We obtained lymphocytes from heparinized blood by Ficoll-Hypaque gradient method, and after the macrophages were removed, they were incubated with 51Cr-labelled K562 cells at concentrations of 100:1, 50:1, 12.5:1 for four hours. We calculated the cytotoxicity activity and lytic unit (LU) of nat...

Extracellular signal-regulated kinases (ERK, also known as mitogen-activated protein kinases) are serine-threonine kinases transducing signals elicited upon ligand binding to several tyrosine kinase-associated receptors. We have reported that ERK2 phosphorylation and activation follows engagement of the low affinity receptor for the Fc portion of IgG (CD16) on NK cells, and is necessary for CD1...

Natural killer (NK) cells mediate antilymphoma activity by spontaneous cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC) when triggered by rituximab, an anti-CD20 monoclonal antibody (mAb) used to treat patients with B-cell lymphomas. The balance of inhibitory and activating signals determines the magnitude of the efficacy of NK cells by spontaneous cytotoxicity. Here, using...

Antibody-based immunotherapy represents a promising strategy to eliminate chemorefractory leukemic cells in acute myeloid leukemia (AML). In this study, we evaluated a novel Fc-engineered antibody against CD157 (MEN1112) for its suitability as immunotherapy in AML. CD157 was expressed in 97% of primary AML patient samples. A significant, albeit lower expression level of CD157 was observed withi...

Antibody-dependent cell-mediated cytotoxicity (ADCC) by natural killer (NK) lymphocytes eliminates cells infected with viruses. Anti-viral ADCC requires three components: (1) antibody; (2) effector the Fc-IgG receptor CD16A; and (3) viral proteins in cell membranes. Fc-afucosylated antibodies bind greater affinity to CD16A than fucosylated antibodies; individuals’ variation afucosylation contri...

Freshly isolated, resting natural killer (NK) cells are generally less lytic against target cells than in vitro interleukin 2 (IL-2)-activated NK cells. To investigate the basis for this difference, the contribution of several receptors to activation of human NK cells was examined. Target-cell lysis by IL-2-activated NK cells in a redirected, antibody-dependent cytotoxicity assay was triggered ...

The spontaneous cytotoxicity of normal human peripheral blood mononuclear cells (PBMCs) is mediated by a subset of lymphocytes called natural killer (NK) cells. Unlike other cytotoxic lymphocytes, which require prior sensitization by the specific antigen to which they are programmed to respond, single NK cells are ?irectly cytotoxic to a wide variety of mahgnant cells without prior exposure. Ne...