Biomedical subjects

O Marder

Publications and source records attributed to O Marder.

8 recordsLinked to original sources

PubMed1998

Costimulatory activity of inactivated influenza virus in response of human peripheral blood mononuclear cells to phytohemagglutinin A and anti-CD3 antibody.

We tested the effect of inactivated influenza A virus on the response of human T lymphocytes to several stimuli. Our results demonstrate that the response to both phytohemagglutinin A (PHA) and anti-CD3 was substantially enhanced by pre-exposure of peripheral blood mononuclear cells (PBMC) to heat-inactivated viral particles, whereas no effect was noted on the proliferative response of PBMC to IL-2. In addition to cell proliferation, exposure of PBMC to viral particles increased the secretion of interferon (IFN)-gamma during stimulation with anti-CD3 antibody and PHA. The costimulatory effect of influenza A virus was reduced by 40% in the presence of 0.1 mM sialic acid. The possible mechanisms involved in the costimulatory effects of influenza A virus are discussed.

Antibodies, Monoclonal↗

PubMed1998

The effect of interferon-gamma and tumor necrosis factor-alpha on the expression of ICAM-1 and HLA-DR molecules on cells of a human germ cell neoplasm and their susceptibility to lysis by lymphokine-activated killer cells.

The ICAM-1 molecule plays a role in the interaction of NK cells with a variety of tumor cells, including carcinoma, melanoma and glioblastoma cells. In the present study, we analyzed the effect of IFN-gamma and TNF-alpha on both the expression of HLA-DR and ICAM-1 molecules on HGCN (Germa-2), and on their susceptibility to lysis by LAK cells. Our results show that 1,000 U/ml IFN-gamma induced a substantial increase in the expression of both ICAM-1 molecules and HLA-DR on the cell surface, while the effect of TNF-alpha on the expression of these molecules was substantially less prominent. When Germa-2 cells, previously exposed to 1,000 U/ml IFN-gamma, were employed as target cells in a 4-hour 51Cr release assay, a statistically significant increase in the lysis by LAK cells was noted. These results show that in the presence of IFN-gamma, Germa-2 tumor cells undergo modulation which affects both the expression of ICAM-1 and HLA-DR molecules as well as their susceptibility to lysis by LAK cells.

Cytotoxicity Tests, Immunologic↗

PubMed1997

Monitoring of effector and target cell stimulation during conjugation by fluorescence polarization.

The aim of the present study was to trace early intracellular changes induced in effector and target cells during their conjugation. This was performed by monitoring the intracellular fluorescein fluorescence polarization (IFFP), using the Cellscan apparatus. This apparatus permits the repetitive spectroscopic measurement of individual selected live cells within a population of many cells, while the location of each cell is known and preserved during the various cell manipulations and/or their suspending medium. Both natural killer (NK) and lymphocyte activated killer (LAK) cells were used as effector cells, while NK-sensitive K562 and NK-resistant Daudi cell lines were used as targets. In this study kinetic IFFP measurements were carried out for a period of approximately 4 h following cell attachment. Within minutes following effector-target conjugation, transient reduction of IFFP was observed consecutively, first in the effector and then in the target cells. A continuous reduction of IFFP occurring only in target cells was also found 50 min following conjugation. No reduction in IFFP was observed using NK- and LAK-resistant target cells. Good correlation was found between early stages of conjugation, as assessed by IFFP, and cytolytic efficiency as assessed by 51chromium release assay. When NK-resistant and LAK-resistant target cells were used, no reduction of IFFP was observed.

Cell Communication↗

PubMed1997

Influenza A virus affects the response of human peripheral blood mononuclear cells to phytohaemagglutinin A by altering the cytoskeleton.

In the present study, we demonstrate that the infection of human peripheral blood mononuclear cells (PBMC) with influenza A virus caused changes in intracellular fluorescein fluorescence polarization (IFFP) which, as previously described, reflect alterations in the polymerization of the cytoskeleton. Kinetic measurements revealed two cycles of an approximate 10% decrease in IFFP within 3.5 and 5 h after infection. Infection win influenza A virus also altered the response of PBMC to phytohaemagglutinin (PHA), which was manifested as changes of 5.3 and 4% in IFFP at 1 and 2 h after infection, respectively. the changes in IFFP correlated with DNA synthesis measured 72 h after exposure to PHA. These results show the ability of IFFP measurements to identify early intracellular metabolic events induced in virus-infected cells.

Cell Division↗

PubMed1997

Infection of K562 cells with influenza A virus increases their susceptibility to natural killer lysis.

Natural killer (NK) cells play a role in the natural immunity against tumor cells. In the present study, we demonstrate that infection of the NK-sensitive tumor cell line K562 with influenza A virus caused a substantial increase in lysis of up to sevenfold when compared to noninfected cells. Similar to NK cells, IL-2-activated killer cells exhibited higher lytic activity against virus-infected K562 cells. This effect of the virus correlated with the increase in the expression of intracellular adhesion molecule-1 (ICAM-1) on K562 cells. Changes in the susceptibility to NK lysis were accompanied by alterations, within minutes, in the cytoskeleton as detected by intracellular fluorescein fluorescence polarization measured on the Cellscan, a static cytometer. The possible role of iCAM-1 and the cytoskeleton in the cytotoxic response of NK cells is discussed.

Cytotoxicity, Immunologic↗

PubMed1996

Decrease of intracellular fluorescein fluorescence polarization (IFFP) in human peripheral blood lymphocytes undergoing stimulation with phytohaemagglutinin (PHA), concanavalin A (ConA), pokeweed mitogen (PWM) and anti-CD3 antibody.

In the present study we describe the induction of changes in intracellular fluorescein fluorescence polarization (IFFP) in lymphocytes undergoing activation with a variety of stimulants. These stimulants included the lectins phytohaemagglutinin (PHA), concanavalin (ConA), pokeweed mitogen (PWM) and anti-CD3 antibody. Changes in IFFP were detected in individual cells using the Cellscan apparatus. Our results show that by employing mitogenic concentrations of PHA, as revealed in a [3H]-thymidine incorporation assay, a decrease in the IFFP in human peripheral blood lymphocytes (PBL) occurred within 40 min. ConA and anti-CD3 affected similarly IFFP, whereas PWM, a B lymphocyte lectin, had no effect on IFFP at the concentrations employed. Kinetic analysis revealed that changes in IFFP occurred within 20-40 min after exposure to the stimulants and lasted for 24 h. Our results show that stimulants which activate CD3+ lymphocytes caused immediate changes in IFFP, in an enriched population of human PBL. The possible mechanisms involved in IFFP modulation following exposure to selected stimulants are discussed.

Antibody Specificity↗

PubMed1996

Effect of interleukin-1 alpha, interleukin-1 beta and tumor necrosis factor-alpha on the intracellular fluorescein fluorescence polarization of human lung fibroblasts.

In the present study we aimed to detect early intracellular changes in the cytoplasmic matrix induced in human, pulmonary-derived fibroblasts following exposure to interleukin (IL)-1 alpha, IL-1 beta and tumor necrosis factor-alpha. Such changes were detected by measuring intracellular fluorescein fluorescence polarization (IFFP) using the Cellscan apparatus. IFFP measurement was selected in our study since it has been shown to reflect the microviscosity of the cytoplasmic matrix. Significant reductions (> or = 5%) in the IFFP were induced in fibroblasts by all the cytokines employed. The effect of cytokines on IFFP was achieved at concentrations of 5-10 ng/ml of the cytokines. The reduction in IFFP, following stimulation with the cytokines, was detected as early as 20 min after exposure to the cytokines, lasted at least 40-60 min after exposure to IL-1 alpha and IL-1 beta, and was inhibited by vinblastine, an inhibitor of the polymerization of microtubules. Our results show that IFFP measurements by the Cellscan may reveal rapid intracellular changes occurring in the cytoskeleton components of activated cells.

Cytochalasin B↗

PubMed1996

Inhibition of mitogen-induced changes in intracellular fluorescein fluorescence polarization of human peripheral blood lymphocytes by colchicine, vinblastine and cytochalasin B.

We have previously reported that the exposure of human peripheral blood lymphocytes (PBL) to a variety of stimulants caused rapid changes in intracellular fluorescein fluorescence polarization (IFFP) in the activated cells. In the present study we further analyzed possible mechanisms responsible for the changes in IFFP in PBL exposed to phytohaemagglutinin (PHA) and anti-CD3 antibody. By employing several agents which are known to affect the polymerization of the cytoskeleton we showed that both cytochalasin B, which regulates the microfilaments structure, and vinblastine and colchicine, which affect the microtubules, completely abolished the changes induced in IFFP of human PBL by both PHA and anti-CD3. This effect was dose dependent and was noted at concentrations ranging from 10 to 100 microM of cytochalasin B and 10 microM of vinblastine and colchicine. The effect of these cytoskeleton modulators occurred within 20 minutes after the initiation of activation with PHA. Our results indicate that activation with PHA and anti-CD3 causes early changes in the microtubules and microfilaments components of the cytoskeleton. The possible application of IFFP measurement in analyzing early changes in the cytoskeleton following cell activation is discussed.

Colchicine↗