Biomedical subjects

A Eisenthal

Publications and source records attributed to A Eisenthal.

At least 19 recordsLinked to original sources

PubMed2000

Absence of RBM expression as a marker of intratubular (in situ) germ cell neoplasia of the testis.

RBM (RNA-binding motif) protein is a marker of male germ cells. This protein is encoded by the Azoospermia factor region-b (AZF-b) of the human Y chromosome and is expressed exclusively in the male germ cell line, that is, spermatogonia, spermatocytes, and round spermatids. The authors analyzed the expression of the RBM gene in germ cell tumors and in the seminiferous tubules in the vicinity of these tumors to identify the presence of IGCN. Sections from testicular germ cell tumors of 21 patients were stained with anti-RBM antibody by using an immunohistochemical method. Distal tubules showing spermatogenesis were immunopositive for RBM protein. All of the germ cell tumors studied were completely immunonegative for RBM. Defined areas of IGCN also showed an absence of RBM expression. Tubules with spermatocyte-like cells, which were expected to express RBM, did not express this protein. This result enabled the identification of tubules as being IGCN. RBM is a novel marker consistently expressed in normal male germ cells but not in malignant germ cell tumors or IGCN. Thus, the absence of RBM expression in germ cells provides a new diagnostic tool of preinvasive malignancy of the testis.

Adult↗

PubMed1999

Exposure of human peripheral blood mononuclear cells (PBMC) to hydrostatic pressure increases their proliferative response to phytohemagglutinin A (PHA) and anti-CD3 antibody.

In the present study we show that a brief exposure of human PBMC to hydrostatic pressure (HyP) increased their proliferative response to PHA and anti-CD3 antibody, assessed by DNA synthesis. The effect of HyP was most prominent at 400 atmospheres of HyP followed by 600 and 200 atmospheres. At any pressure level, the highest effect of HyP was noted when employing PHA and anti-CD3 antibody at 10(-2) dilution. When PBMC were exposed to 400 atmospheres HyP, maximal effect was achieved at 20 minutes of exposure. The highest effect of HyP on DNA synthesis was noted at 48 and 72 hours of incubation with PHA, when exposing cells to pressure for 20 minutes at 400 atmospheres. Exposure of PBMC under similar conditions for 40 minutes, caused an increase in DNA synthesis only at 48 hours incubation with PHA. These results demonstrate that exposure of human PBMC to HyP increases their proliferative response to different polyclonal activators. The possible mechanisms involved in this phenomenon are discussed.

Antibodies↗

PubMed1998

Human tumor cells, modified by a novel pressure/crosslinking methodology, promote autologous lymphocyte proliferation and modulate cytokine secretion.

Hydrostatic pressure (P) combined with membrane protein crosslinking (CL) by adenosine dialdehyde (AdA) can render tumor cells immunogenic. We have recently shown that PCL treatment of murine tumor cells augmented the presentation of MHC-restricted tumor-associated antigens and enhanced cell-mediated immunity. In cancer patients inoculated with autologous PCL-modified tumor cells, a significant delayed-type hypersensitivity response was elicited. Since the balance between cell-mediated immunity and humoral immunity is reciprocally controlled by immunoregulatory cytokines, we have examined the proliferative response and cytokine secretion pattern in cultures of human peripheral blood mononuclear cells (PBMC) stimulated by autologous PCL-modified and unmodified tumor cells. These tumor cells were obtained from freshly resected tumor tissue of 16 patients with colon (8), lung (4) and renal (4) carcinomas. The results demonstrated that PCL-modified tumor cells promoted an increase in PBMC proliferation in 5 out of 8 (63%), 1 out of 4 (25%) and 4 out of 4 (100%) colon, lung and renal cell carcinomas. Fourteen of the above cultures were also analyzed for the secretion of interleukin-10 and interferon-gamma. Overall, a substantial decrease in IL-10 secretion was detected in 9 out of 14 (64%) cultures while a reciprocal increase in interferon-gamma secretion was noted in 8 out of 14 (57%) cultures. Our results confirmed that PCL-modified human tumor cells of different etiologies can modulate the pattern of cytokines released from stimulated autologous lymphocytes. Such a procedure could prove valuable in the production of autologous tumor vaccines.

Carcinoma↗

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

Increased microvascular permeability induced by prolonged interleukin-2 administration is attenuated by the oxygen-free-radical scavenger dimethylthiourea.

Effective use of interleukin (IL)-2 as an antineoplastic agent may be hindered by severe side-effects, in particular vascular leak syndrome, which leads to generalized, especially pulmonary, edema. The oxygen-free-radical scavenger dimethylthiourea (DMTU) was shown to attenuate IL-2-induced vascular leak syndrome in sheep receiving a single IL-2 injection. However, in the clinical setting multiple injections are necessary to gain a therapeutic effect. The present study tests whether DMTU attenuates IL-2-induced vascular leak syndrome following multiple IL-2 injections without affecting IL-2-induced cytotoxicity in peritoneal mononuclear cells. Mice were treated intraperitoneally with 1 x 10(5) units IL-2 three times daily for four consecutive days. DMTU (10 mg/0.5 ml) was administered to the study group once daily, prior to the first IL-2 injection. Comparing the wet/dry weight ratio of lungs, liver, and spleen showed that IL-2 caused a significant (P < 0.05) wet/dry increase in all three organs. DMTU attenuated the wet/dry increase in the lungs (P < 0.05), in the spleen (P < 0.05), and not at all in the liver. IL-2 induced a marked increase in peritoneal mononuclear cell counts, which was not attenuated by DMTU. The cytotoxic effect of IL-2-activated peritoneal mononuclear cells on target B16 cells was also unchanged in animals pretreated with DMTU. In conclusion, we have shown that DMTU ameliorates pulmonary permeability and vascular leak syndrome associated with multiple-dose IL-2 therapy, without eliciting an inhibitory effect on IL-2 induced-cytotoxicity.

Animals↗

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

Surface projection of murine major histocompatibility determinants induced by hydrostatic pressure and cytokines.

Augmentation of surface presentation of the major histocompatibility complex (MHC) is a leading trend for preparation of tumor vaccines. Exposure of weakly immunogenic tumor cells, such as murine B16 melanoma, to hydrostatic pressure (P) in the presence of the membrane-impermeable protein crosslinker (CL) 2',3'-adenosine dialdehyde, was previously shown to induce a substantial increase in surface presentation of MHC molecules. When B-16 melanoma cells, used here as a model, were first treated for 72 h with interferon-gamma or tumor necrosis factor-alpha at concentrations of 10 and 100 units/ml, respectively, followed by application of pressure and cross-linking (PCL), the surface presentation of H2b molecules increased by 40% compared to treatment with cytokines alone, and by up to 1,700% when compared to treatment with PCL alone. Neither P nor CL alone enhanced the MHC presentation when cells were pretreated with these cytokines. The changes in MHC observed after the cytokine treatment were transient and decayed within several hours. However, the changes induced by the sequential treatment with cytokines and PCL were sustained for at least 96 h post-PCL which is of prime importance for immunogenic expression. A series of analogous experiments in the presence of cycloheximide indicated that approximately 50% of the observed PCL-induced increase in MHC projection originates from protein synthesis while the other 50% corresponds to passive translocation of MHC compartments. B16 melanoma cells, modified by the sequential treatment of cytokines and PCL, proved to be substantially more immunogenic by an in vitro sensitization assay than cells treated by either one of these treatments alone. These results may provide a guideline for the preparation of tumor vaccines which could be applied in immunotherapy treatment of cancer.

Animals↗

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↗

PubMed1995

Fluorescence polarisation changes in lymphocyte cytoplasm as a diagnostic test for breast carcinoma.

Lymphocytic cytoplasm from individuals with malignant disease, and from those without, differ in such a way as to be diagnostic both of malignancy generally and of specific types of cancer. Mitogenic stimulation of lymphocytes by phytohaemagglutinin (PHA) and antigenic stimulation by encephalitogenic factor (EF) and certain specific tumour-associated antigens, provokes changes in the structure of the cytoplasmic matrix (SCM) which are detectable upon fluorescence polarisation. The degree of change is quantifiable both by calculating the polarisation ration (PR, polarisation before and after stimulation) and the relative ratio (RRSCM, the ratio between the polarisation obtained after exposure to EF [PEF] and to the polarisation measured after exposure to PHA [PPHA]). A new tumour-associated antigen specific for breast cancer, CaBr, was tested for its diagnostic efficacy in comparison with that of EF, by prospectively testing blood samples from 138 consecutive women with suspicious breast masses. The previously known discriminatory power (sensitivity 60.7% and specificity 90.7%) of the polarisation-derived RRSCM was reconfirmed. However, the RR'SCM (the new ratio using CaBr instead of EF), was significantly more sensitive (77.4%; P < 0.01) and specific (94.4%) than the RRSCM in detecting breast cancers. The polarisation changes in the cytoplasmic matrix after stimulation by CaBr alone suggest the best discriminatory power (sensitivity 90.5% and specificity 94.4%) between cancerous and non-cancerous patients.

Adult↗

PubMed1994

A phase II study of combined administration of dacarbazine and carboplatin with home therapy of recombinant interleukin-2 and interferon-alpha 2a in patients with advanced malignant melanoma.

Chemotherapy and interleukin-2 (IL-2) and/or interferon alpha (IFN alpha) produce objective responses in a proportion of patients with advanced malignant melanoma. The duration of response to chemotherapy is usually less than 4 months, and immunotherapy has resulted in long-lasting remissions in a small number of patients with metastatic melanoma. The current study was conducted to improve the antitumor efficacy and the interactions between recombinant (r) IL-2, rIFN alpha 2a and chemotherapy. A total of 16 evaluable patients with metastatic malignant melanoma were entered into a phase-II study designed to assess the response rate and therapeutic efficacy of dacarbazine and carboplatin followed by rIL-2 and rIFN alpha 2a. Patients received 750 mg/m2 dacarbazine with 400 mg/m2 carboplatin each by intravenous bolus on days 1 and 22. Recombinant IL-2 and IFN alpha 2a were administered on an outpatient basis (home therapy) subcutaneously for 6 consecutive weeks: 4.8 x 10(6) IU/m2 rIL-2 daily, 5 days a week; 6.0 x 10(6) IU/m2 rIFN alpha 2a thrice weekly. There were responses in 6 of the 16 enrolled patients with an overall response rate of 37.5% (95% confidence interval: 14%-61%). All responding patients had partial responses. The median survival time of the responding patients was significantly better than that of patients with progressive and stable disease (P = 0.03). The median duration of response was 11 months (range 2-24 months). Responses in lung, liver, soft tissue and lymph-node sites were noted.

Adolescent↗

PubMed1994

Inhibition of CT-26 murine adenocarcinoma growth in the rectum of mice treated with recombinant human interleukin-6.

In the present study we evaluated the antitumor effects of recombinant human interleukin-6 (rhIL-6), expressed in Chinese hamster ovary cells, in a murine primary tumor model. We showed that treatment with rhIL-6 substantially inhibited the implantation and growth rates of CT-26 adenocarcinoma tumor cells in the rectal submucosa of syngeneic mice. This effect was achieved by injecting rhIL-6 for 7 consecutive days starting 1 day prior to tumor inoculation. No obvious antitumor effect was noted when rhIL-6 injections started 5 days after tumor inoculation. Analysis of the mechanisms by which rhIL-6 exerts its antitumor effects did not reveal a direct antitumor effect on CT-26 tumor cells or the up-regulation of major histocompatibility complex antigens on these cells. However, infiltration of lymphocytes at the tumor site was observed. Increase of carcinoembryonic antigen by IL-6 was clearly seen in human HT-29 colon carcinoma cells. The possible application of these results for adjuvant immunotherapy of selected colorectal patients and prevention of reimplantation of tumor cells disseminated during surgery is discussed.

Adenocarcinoma↗

PubMed1993

Effect of allogeneic tumor cells, interleukin-2 and interleukin-6, on the growth of subcutaneous syngeneic tumors.

In the present study we demonstrate the ability of allogeneic M3 tumor cells to induce an antitumor response against the syngeneic tumor, when injected locally together with syngeneic B16 melanoma cells. The replacement of the allogeneic tumor cells with either syngeneic or allogeneic splenocytes had no effect on the growth of the syngeneic tumor. Systemic administration of both interleukin-2 (IL-2) and IL-6 did not affect the antitumor response induced by allogeneic tumor cells. When mice, previously injected with B16 and M3 cells, were rechallenged subcutaneously with B16 tumor cells at a different anatomical site, an inhibitory effect in some, but not all, experiments was observed. Systemic injections of either IL-2 or IL-6 did not alter the antitumor effects of the allogeneic and syngeneic tumor-cell mixtures. The significance of our results in developing immunotherapy modalities based on active immunization with allogeneic tumor cells and selected cytokines is discussed.

Animals↗

PubMed1993

Phenotypic and functional profile of peripheral blood mononuclear cells isolated from melanoma patients undergoing combined immunotherapy and chemotherapy.

In the present study we tested the phenotypic profile as well as several immunological responses of peripheral blood mononuclear cells (PBMC) isolated from melanoma patients. These patients underwent chemotherapy with dacarbazine and carboplatin from day 1 to day 22, followed by immunotherapy of low-dose recombinant interleukin-2 and recombinant interferon alpha administered subcutaneously from day 36 to day 75. The PBMC from 14 patients were isolated on day 0 before chemotherapy, on day 36 after chemotherapy and on day 76 after immunotherapy. After chemotherapy, a decrease in CD16+ cells and increase in CD3+ and CD4+ cells correlated with a significant decrease in the generation of lymphokine-activated killer (LAK) activity. After immunotherapy, an increase in CD16+ cells correlated with an increase in the induction of LAK activity. A comparison between responding and non-responding patients revealed statistically significant differences in LAK activity of PBMC and response to concanavalin A following chemotherapy, and in the percentage of CD8+ cells following immunotherapy. Our results point toward the value of continuing such a study on a larger population of cancer patients in order to select the appropriate bioassays for monitoring and predicting the clinical responsiveness to combined therapies.

Adult↗