Search PubMed⌕ Search

Biomedical subjects

E Klein

Publications and source records attributed to E Klein.

At least 343 records · Page 19Linked to original sources
PubMed1985

Effect of cyclosporin-A (CsA) on the ability of T lymphocyte subsets to inhibit the proliferation of autologous EBV-transformed B cells.

We have analyzed the effect of Cyclosporin-A (CsA) on the in vitro suppression of Epstein-Barr virus (EBV)-induced B-cell proliferations separated on the basis of cell density. CsA abolished the growth-inhibitory capacity of high-density T cells but influenced only marginally the activity of low-density lymphocytes; this suggested that different mechanisms mediate suppression in the two subsets. Stimulation with irradiated EBV-transformed cells had a different impact on the activity of low- and high-density lymphocytes. Proliferative and cytotoxic responses were inversely correlated, i.e. high-density cells proliferated but exerted low cytotoxicity, while the lytic activity of the low-density subset was stronger in the absence of significant cell proliferation. Proliferation and generation of cytotoxicity were abrogated by CsA in both subsets. The activities could be restored by addition of exogenous IL-2, suggesting that the drug may interfere with the cascade of lymphokine--cell interactions which leads to activation of immune responses. From the analysis of athe CsA effects on the two subsets it seems that the high-density one contains specific memory T cells which are activated and proliferate upon encounter with EBV-infected cells. On the other hand, low-density lymphocytes are induced to release soluble factors with antiproliferative activity. The secretory function was resistant to the suppressive effect of CsA.

B-Lymphocytes↗
PubMed1985

Mapping the functional topography of Fc gamma with monoclonal antibodies: localization of epitopes interacting with the binding sites of Fc receptor on human K cells.

A panel of monoclonal antibodies (mAb) specific for the C gamma 2, C gamma 3 or inter C gamma 2/C gamma 3 domain epitopes was tested for inhibition of antibody-dependent cellular cytotoxicity (ADCC) specific for anti-D IgG-coated erythrocytes. Significant inhibition of ADCC was demonstrable for some antibodies having specificity for C gamma 2 or C gamma 3 domain epitopes, while others gave no inhibition. Fab fragments of a representative C gamma 2-specific antibody (A55) and C gamma 3-specific antibody (x3a8) retained their inhibitory capacity in lymphocyte-mediated ADCC, but only A55 Fab inhibited monocyte-mediated lysis. Furthermore, the Fab portion of A55 completely abolished the complement-dependent enhancement of ADCC mediated by concanavalin A-stimulated cells, while x3a8 Fab had no effect in this system. On the other hand, x3a8 Fab inhibited the binding of anti-D IgG-sensitized erythrocytes to lymphocytes while A55 Fab did not influence this latter interaction. The results suggest that C gamma 2 domain-FcR interaction is essential for the triggering of lytic process both in lymphocyte and in monocyte-mediated ADCC, while C gamma 3 domain has no role in the latter but is responsible for the appropriate contact between effector lymphocytes and target cells. A site in the region of Lys274 appears to be critical for triggering of both lymphocyte and monocyte-mediated ADCC.

Antibodies, Monoclonal↗
PubMed1985

DR antigens expressed on tumor cells do not contribute to the blastogenetic response of autologous T cells.

Tumor cell suspensions prepared from surgical specimens were characterized for cellular composition and reactivity with monoclonal antibodies detecting T lymphocytes, monocytes, and the monomorphic determinants of DR molecules (antigens encoded by the D region of the major histocompatibility complex in man). About half the adenocarcinoma preparations contained tumor cells which expressed DR antigens. Lymphocytes of certain patients were stimulated in vitro by the autologous tumor cells, and this was independent of the expression of DR antigens on the tumor cells. In addition, pretreatment of the stimulator tumor cells with anti-DR Mab (monoclonal antibody) had only marginal effect on their stimulatory potential. In contrast, when the same tumor cells were used as stimulators of allogeneic lymphocytes, proliferation was more often seen with DR-positive tumors and the reaction was often inhibited by the anti-DR Mab treatment. There were exceptions, however, which suggest that other DR antigens not detected by the reagents used may have been expressed on these cells. The allostimulatory capacity of the tumor cells was usually weak and did not occur with all responder lymphocytes. It is important to note that stimulation of autologous lymphocytes could occur with tumor preparations that did not elicit allogeneic response. Thus, the in vitro stimulation of autologous blood-derived T cells by suspensions of unpropagated cells separated from solid tumors reflects the sensitization state of the patients against their tumor cells.

Adenocarcinoma↗
PubMed1985

Modulation of human blood lymphocyte cytotoxicity by the phorbol ester tumor promoter P(Bu)2: increase of target binding, impairment of effector recycling, and activation of lytic potential which is independent of IL-2.

Treatment of lymphocytes with the tumor promotor P(Bu)2 enhanced their target-binding capacity. In the conventional 51Cr-release assay, the cytotoxic potential of lymphocytes pretreated with P(Bu)2 for a short time was reduced while after prolonged treatment their function was increased. The peak of lytic potential was attained after 15 hr of exposure. Comparison of the cytotoxic results obtained in suspension and immobilized conjugate assays suggested that P(Bu)2 treatment causes an impairment of the recycling capacity of lymphocytes. After prolonged exposure, the lytic machinery became activated as reflected by the reduced time elapsing after contact between effectors and targets and the delivery of lethal hit. The activation was also observed in the immobilized agarose assay. It was reflected by the elevated proportion of damaged targets that were bound to the treated lymphocytes. The P(Bu)2- and interferon-induced augmentation of lytic potential is achieved through different mechanisms. Combination treatment applied to the effectors in sequence (first P(Bu)2 followed by interferon), resulted in an additive effect. Similarly, simultaneous treatment with IL-2 and P(Bu)2 also gave an additive increase in cytotoxicity. Addition of antibodies directed against IL-2 did not abrogate the P(Bu)2 effect. Consequently, neither interferon nor IL-2 are involved in the phorbol ester-induced cytotoxic function.

Animals↗
PubMed1985

Selective inhibitory effect of Hu-IFN-gamma on the agarose clonability of tumor-derived lymphoid cell lines.

Recombinant human interferon alpha (IFN-alpha) and interferon gamma (IFN-gamma) were compared for their ability to influence the proliferative capacity of tumor-derived cell lines and of normal B lymphocytes infected in vitro by Epstein-Barr virus (EBV). EBV-induced B-cell proliferation was suppressed almost completely when 10(2) U/ml IFN-alpha were added to the culture medium while the same dose of IFN-gamma had significantly lower inhibitory activity. The pure IFNs differed in their ability to influence the growth of three Burkitt lymphoma-derived cell lines, Raji, Daudi, and Namalwa, depending on whether the cells were propagated in suspension or in semisolid cultures. IFN-alpha inhibited cell proliferation under both culture conditions with thresholds of sensitivity characteristics for each cell line. In contrast, IFN-gamma had no effect on the growth in suspension but it abolished the clonogenic potential of tumor cell lines in semisolid agarose. The results suggest that the two IFN types may exert their growth inhibitory activity through different mechanisms of action.

B-Lymphocytes↗
PubMed1985

Leukocyte migration inhibitory factor production by activated lymphocytes representing immunological memory or virus-receptor interaction: response of T cell subsets to Epstein-Barr virus nuclear antigen, response of B cells to UV inactivated Epstein-Barr virus.

Both T and B lymphocytes are known to produce leukocyte migration inhibitory factor (LIF) after appropriate activation. We showed that EBV nuclear antigen (EBNA) triggered T cells for LIF production in an immunologically specific way: only T cells of seropositive individuals responded. Both Fc receptor positive and negative T cells produced LIF, and the presence of macrophages was necessary. The virus itself activated B cells independently of the serological status of the donors, thus the function was not based on immunological memory. This phenomenon was independent of the transforming capacity of the virus, because UV-inactivated virus also elicited LIF production by B lymphocytes. This triggering seems to be the consequence of the virus-receptor interaction on the cell surface.

Antigens, Viral↗
PubMed1985

Induction of K562 lysis in autologous LGL and dense T cell cocultures.

Human large granular lymphocytes (LGL) were cultured with autologous dense T lymphocytes for 0-8 days. The mixed LGL dense T cell cultures had enhanced lytic activity against K562 on day 4, as compared to LGL cultured alone. Dense T cells cultured alone had no K562 lytic activity. The mixed LGL dense T cell cultures were reseparated on day 4 into low dense SRBC- and SRBC+ and into high dense subsets. Both low dense subsets did lyse K562 whereas the high dense subset did not lyse K562. Since the LGL population was the low dense SRBC- cells, the results suggested that the day 4 low dense SRBC+ cytotoxic population in the mixed LGL dense T cell culture originated from noncytotoxic dense T cells. Dense T cells were also separated into OKT8- and OKT8+ subsets and cultured together with LGL for 0-8 days. The LGL dense OKT8- T cell coculture had enhanced K562 lytic activity while the LGL dense OKT8+ T cell coculture had no enhanced lytic activity, as compared to LGL cultured alone. These results indicated that LGL interacted with the dense OKT8- T cells to produce the enhanced K562 lysis.

Antibodies, Monoclonal↗
PubMed1985

Activation of human blood lymphocytes and monocytes by the streptococcal preparation OK432: enhanced generation of soluble cytotoxic factors.

The streptococcal preparation OK432 augments natural cytotoxicity of human blood lymphocytes and monocytes. It also enhanced the production of natural killer soluble cytotoxic factors (NKCF) when the effector cells interact with K562 cells. There was a good correlation between the OK432-induced enhancement of NK cell-mediated cytotoxicity and the released NKCF activity. OK432-pretreated monocytes secreted higher amounts of monocyte cytotoxic factors (MCF) than the untreated monocytes. With the monocytes the enhanced generation of MCF was not always accompanied by the increase in direct cell-mediated lysis of K562. OK432 treatment alone did not induce NKCF release from lymphocytes, and the presence of K562 in the culture was necessary. In contrast, monocytes generated MCF when exposed to OK432. In the supernatants of cocultures of OK432-activated effectors and K562 the NKCF and MCF activity was elevated two- to ten-fold. The OK432-induced augmentation of natural cytotoxicity exerted by lymphocytes and monocytes may be mediated through an increase in the synthesis, activation and/or release of NKCF and MCF.

Biological Products↗
PubMed1985

Specific and non-specific components in the triggering of proliferative and cytotoxic responses of T lymphocytes with different cell density.

We hve analyzed the functional behavior of lymphocyte subsets separated on the basis of cell density. Low and high density subpopulations were cultured in FCS, alone or with allogeneic irradiated PBL, and then examined for proliferation and cytotoxic activity against autologous (responder) and allogeneic (stimulator) PHA-induced blasts, K562 and Daudi. In the high density subset proliferation and generation of anti-K562 and anti-Daudi effects were induced by FCS and to higher extent by allospecific stimulation. Exposure to alloantigens induced allospecific cytotoxicity. Autologous PHA blasts were not affected. The results with the low density subset differed. Independently of the type of stimulus imposed, the low density fraction showed little if any proliferation, but its cytotoxic activity was stronger against all targets tested. In some of the experiments, anti-alloblast cytotoxicity was generated in the control cultures. Thus, polyclonal activation induced by FCS triggered in this fraction allospecific cytotoxicity. In this subset, the effect against allogeneic PHA blasts comprised a specific and a non-specific component because autologous PHA blasts were also lysed. Limiting dilution analysis involving allostimulation showed higher frequency of cytotoxic precursors in the low density subset. Split minicultures were tested for lysis of auto- and allogeneic blasts. Alloreactive cultures that did not lyse the autologous target were more frequent in the cultures initiated with the high density cells. There was no conclusive evidence for the existence of autoreactive cultures that did not lyse the allogeneic blasts.

Animals↗
PubMed1985

Complement-dependent cellular cytotoxicity: lymphoblastoid lines that activate complement component 3 (C3) and express C3 receptors have increased sensitivity to lymphocyte-mediated lysis in the presence of fresh human serum.

Lymphocyte-mediated lysis of cells of the Raji, Daudi, Jijoye, and Bjab lines was elevated when fresh human serum was added to the assay. A higher proportion of effector-target conjugates was observed in the presence of human serum. In similar experiments lysis of 1301, Rael, and P3HR-1 cells was unaltered. All cell lines activated the alternative pathway of complement but they varied in the expression of receptors for complement component 3 (C3) and in the ability to fix the C3 cleavage products on their membrane. The enhancement of lysis in the presence of human serum occurred only with those cells that bound C3. This characteristic was correlated to the expression of C3 receptors. Analysis of the nature of the deposited C3 was performed with Raji cells. Raji cells exposed to human serum bound C3b as indicated by the immunoadherence test. The C3b was further processed to C3bi, because the immunoadherence declined with time and conjugate formation increased with Daudi cells, which carry the C3 receptors CR2 and CR3. This suggests that in the lytic assay lymphocytes with C3bi receptors are recruited in the presence of human serum. We assume that the bridge of C3 molecules between targets and effectors increases the avidity of their interaction.

Burkitt Lymphoma↗
PubMed1985

Natural cytotoxicity of human blood lymphocytes and monocytes and their cytotoxic factors: effect of interferon on target cell susceptibility.

The effect of interferon (IFN) on target cell susceptibility to human natural killer (NK) cells and monocytes was analyzed in direct cell-mediated and their cytotoxic factor-mediated cytotoxicity assays. Treatment of K562 cells with IFN resulted in a decrease in their sensitivity to lysis by nonadherent lymphocytes and Percoll-purified large granular lymphocytes (LGL) when tested in a 4-hour 51Cr release assay. In contrast, the treatment did not affect the target susceptibility to monocytes purified by adherence to autologous serum-coated plastic surfaces. In the target-binding assay with LGL or monocytes the number of conjugates was not altered after IFN treatment of K562. Lymphocytes and monocytes were induced to release soluble cytotoxic factors, termed "natural killer cytotoxic factors (NKCF) and monocyte cytotoxic factors (MCF)," respectively, when co-cultured with K562. Both NKCF and MCF lysed K562 in a 48-hour microcytotoxicity assay or in an 18-hour 51Cr release assay in the presence of dactinomycin. IFN-treated K562 reduced or completely lost their ability to stimulate the release of NKCF, whereas they triggered MCF secretion as effectively as did the untreated K562. When lymphocytes or monocytes were pretreated with IFN, they released NKCF or MCF with augmented lytic activity. In contrast to the sensitivity to NK cell-mediated lysis, IFN pretreatment of K562 induced no change in their susceptibility to NKCF and MCF. When IFN was added to NKCF and MCF assays, the cytotoxicity was enhanced. The addition of IFN to K562 that had been pretreated with NKCF or MCF and washed resulted in no increase in lysis. The capacity of K562 to absorb the lytic activity of NKCF and MCF was not altered by IFN. These results indicate that IFN treatment of target cells can be used to distinguish the two distinct types of blood mononuclear cells with natural cytotoxicity, NK cells and monocytes, and that each effector cell type is stimulated to release cytotoxic factors by the different target determinant after the initial effector-target cell binding.

Cytotoxicity, Immunologic↗
PubMed1985

Evaluation of a peritoneal dialysis solution containing polymer.

Glucose is used in peritoneal dialysate to produce the gradient for ultrafiltration. The peritoneal membrane's low reflection coefficient for glucose imposes a demand for high transmembrane concentrations, perhaps adding unwanted body burden of glucose. A polymer with a lower permeation rate used as an osmotic agent would circumvent this. We evaluated the mass transfer coefficient (mtc), T1/2 disappearance from the peritoneal cavity and ultrafiltration capabilities of a 900 dalton (Mn) starch derived polymer. We compared an 8% (455 mOsm/L) and a 10% (484 mOsm/L) polymer (Pol) solution to available dialysate solutions containing 2.5% (399 mOsm/L) and 4.25% (491 mOsm/L) X glucose (Glc). The dialysate compositions were otherwise similar. Using a randomized complete block design, 5 anephric dogs maintained on chronic peritoneal dialysis were studied. The mtc (ml/min) was greater for the glucose than the polymer solutions (p less than 0.05): 2.5%-13 and 4.25%-14 vs 8%-5 and 10%-6. The T1/2 disappearance (min) was also greater (p less than 0.05): 2.5% Glc-112 and 4.25% Glc-111 vs 8% Pol-281 and 10% Pol-252. Over a 180 min. period the 2.5% glucose solution generated the least volume of ultrafiltrate (ml, p less than 0.05): 2.5% Glc-113 and 4.25% Glc-589 vs 8% Pol-640; 10% Pol-912. We conclude that the lower permeation rate of the polymer yields ultrafiltration at a lower dialysate osmolality. A polymer solution may be a feasible alternative to glucose.

Animals↗
PubMed1985

A comparison of lithium effects on human brain and rat brain noradrenaline-sensitive adenylate cyclase.

Lithium (Li) is a drug with numerous biochemical effects. Many of these biochemical effects occur only at high Li concentrations, or disappear after chronic Li treatment. Such effects are probably not related to Li's mechanism of therapeutic action. Inhibition of noradrenaline (NE)-sensitive adenylate cyclase has been proposed as a possible therapeutic mechanism of action for Li. Tolerance does not develop to this effect, which has been reported to occur reliably beginning at 2mM Li in rat cortex. Since 2mM Li is at the upper limit of therapeutic levels in humans, controversy has continued as to whether Li inhibition of NE-sensitive adenylate cyclase is a mechanism of Li's therapeutic action or a mechanism of Li toxicity. We hypothesized that human brain NE-sensitive adenylate cyclase may be more sensitive to Li inhibition than rat brain NE-sensitive adenylate cyclase. Fresh cortical human grey matter was obtained from the edges of surgically removed brain tumors in seven patients. Results showed significant inhibition of NE-sensitive adenylate cyclase at 1mM Li. These results support the possibility that inhibition of NE-sensitive adenylate cyclase is a mechanism of Li's therapeutic action.

Adenylyl Cyclase Inhibitors↗
PubMed1985

Substitution of a starch polymer for glucose in peritoneal dialysis.

We compared a starch-derived polymer (molecular weight = 900) as the osmotically active agent in peritoneal dialysate (3 and 6% solutions) to results obtained with commercially available glucose dialysate (1.5 and 4.25%). 12 dogs were dialyzed with glucose for 7 days, and 9 received the polymer for 5 days. For dialysate exchanges with an intraperitoneal residence of 240 min the 1.5 and 3% solutions generated similar volumes of ultrafiltrate as did the 4.25 and 6% solutions. However, for exchanges of 960 min the 1.5% dialysate was significantly reabsorbed when compared to the other dialysate concentrations. The serum polymer concentration increased with continued dialysis. The rate of transfer from dialysate to serum in man must still be determined. The lower diffusivity of the polymer will certainly be evidenced. For certain clinical applications where diminished ultrafiltration occurs, the polymer may be of benefit to man.

Animals↗