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Biomedical subjects

M Jondal

Publications and source records attributed to M Jondal.

At least 127 records · Page 7Linked to original sources
PubMed1987

The adenosine receptor mediated accumulation of cyclic AMP in Jurkat cells is enhanced by a lectin and by phorbol esters.

The accumulation of cyclic AMP in Jurkat cells was stimulated by adenosine and adenosine analogues. The accumulation of cyclic AMP induced by these agents was competitively antagonized by the adenosine receptor antagonist 8-p-sulphophenyl-theophylline (KD appr 1.9 microM). The lectin PHA, the diacylglycerol OAG as well as tumor promoting phorbol esters enhanced the accumulation of cyclic AMP induced by the adenosine analogue NECA. The results suggest that activation of CD2/CD3 receptors by lectins could potentiate the endogenous cyclic AMP stimulator adenosine via activation of protein kinase C.

Adenosine↗
PubMed1987

1,25-Dihydroxyvitamin D3 and phorbol esters (TPA) may induce select in vitro differentiation pathways in the HL60 promyelocytic cell line.

Monocytic features can be induced in the myeloid cell line HL60 in order to provide a suitable in vitro model for the investigation of in vitro activity in mononuclear phagocytes. 1,25-Dihydroxyvitamin D3 (calcitriol) induced the HL60 cell line to express the monocytic differentiation antigen Leu M3 in about 30-50% of the cells along with an increase (up to 20%) in the expression of HLA-DR but not HLA-DQ class II antigen. Functional investigation showed that calcitriol-treated cells formed rosettes with sheep erythrocytes coated with an anti-sheep erythrocyte-specific IgG2a mouse MoAb and readily ingested them. In addition, these same sensitized erythrocytes were lysed in an 18-hr antibody-dependent cellular cytotoxicity (ADCC) assay. All together these data indicate the presence of functionally active Fc-IgG receptors (FcR). Sorting experiments demonstrated that only Leu M3+ HLA-DR+ cells contained the effector cell population; such was also the case for blood monocytes. This phenotypic profile was, however, not predictive per se of FcR presence and function, as 12,O-tetradecanoylphorbol-13-acetate (TPA)-induced HL60 cells neither formed rosettes nor phagocytosed nor exhibited ADCC activity, although they express Leu M3 and HLA-DR (as well as HLA-DQ) antigens. These results suggest that calcitriol and TPA cause the differentiation of HL60 cells along distinct pathways. On the other hand, different subpopulations with given predetermined differentiation capabilities may coexist in HL60 cell line. This hypothesis gains support by the observation that when TPA and calcitriol were added together to the undifferentiated cells, the resulting phenotypic pattern was representative of the different activities of both of the inducers as they were used separately.

Antigens, Neoplasm↗
PubMed1987

Characterization of PHA and anti-T3 induced transduction mechanisms in a human T-cell leukaemia line.

Stimulation of the T-cell line JURKAT with PHA or anti-T3 antibody leads to a rapid and sustained rise of cytosolic free Ca2+, as determined by quin2 fluorescence measurements. Pertussis toxin and N-ethylmaleimide, substances known to inactivate a regulatory N-protein, caused partial to complete inhibition of the cytosolic free Ca2+ response induced both by anti-T3 or PHA. The high cytosolic free Ca2+ level induced by anti-T3 or PHA declined more rapidly after addition of phorbol ester, phorbol myristate acetate (PMA). PMA did not affect cytosolic free Ca2+ changes induced by ionomycin indicating that the effect of PMA is due to a direct inhibitory effect on a transduction mechanism and not to activation of Ca2+ extrusion. Our data suggest that a regulatory N-protein is involved in the transduction of the PHA and anti-T3 response into a rapid and sustained elevation of cytosolic free Ca2+. Activation of protein kinase C by PMA modulates the calcium response in JURKAT cells, suggesting that protein kinase C may be involved in feedback regulation of the transduction mechanism.

Calcium↗
PubMed1987

Spontaneous production of interleukin 1 activity by chronic lymphocytic leukemic cells.

Chronic lymphocytic leukemic B cells (B-CLL) were found to produce an IL 1-like growth factor spontaneously in vitro for mouse thymocytes. This factor was comitogenic with concanavalin A (Con A) and nonmitogenic combinations of phorbol ester and calcium ionophore but not with phyto-hemagglutinin (PHA). Growth factor production was dose-related to the number of in vitro cultured cells and detectable at 6 hours using high cell concentrations. A small number of admixed normal T cells was not important for factor production. No growth of autologous B-CLL or allogeneic thymocytes was induced by the factor. A chromatographic high-performance liquid chromatography (HPLC) analysis and inhibition experiments with a polyclonal rabbit anti interleukin 1 (IL 1) antiserum indicated that the B-CLL-derived growth factor belonged to the IL 1 family. This was supported by the direct demonstration of IL 1 beta in supernatants from B-CLL by radioimmunoassay. Possible biologic implications for B-CLL-derived IL 1 are discussed in relation to tumor cell growth in different clinical stages.

B-Lymphocytes↗
PubMed1986

Monoclonal antibodies against the NK cell-FcR and the T3-complex potentiate normal lymphocyte killing.

Pretreatment of normal human lymphocytes with monoclonal IgG against the NK cell-FcR (IgG) or the T3 complex was found to potentiate killing of most NK sensitive target cells with the exception of T-cell derived cells. Anti-FcR IgM monoclonals were suppressive for all target cells. IgG anti-FcR mediated potentiation required minute amounts of antibody but was also seen at high anti-FcR concentrations that modulated FcR activity. Potentiated and FcR modulated cells retained anti-FcR IgG on the membrane and conjugated normally to target cells. Anti-FcR potentiation blocked antibody-dependent killing but did not influence lectin-dependent killing, with anti-T3 the opposed effect was seen. Combined anti-FcR and anti-T3 treatment resulted in decreased potentiation. The results suggest that the NK cell-FcR may be activated during normal NK cell killing (without the addition of antibody) as suggested for FcR in B cell triggering.

Antibodies, Monoclonal↗
PubMed1986

Natural killer and T-cell potentiation by monoclonal IgG against natural killer cell FcR(IgG) or the T3 complex.

Treatment of human natural killer (NK) cells with monoclonal antibodies of the IgG isotype against NK cell-FcR(IgG) increased lysis of most haematopoietic target cell lines with high or intermediate background NK susceptibility. Treatment of normal non-adherent lymphocytes with an IgG anti-T3 monoclonal antibody also increased lysis against the same target cells. Potentiating anti-FcR antibodies rapidly modulated FcR activity and the capacity of the cells to act as antibody-dependent killers, although such antibodies were demonstrable for a long time at the cell surface. Anti-FcR treatment did not influence concanavalin A (Con A)-dependent killing, in contrast to anti-T3 treatment, which suppressed lectin-dependent lysis but did not influence antibody-dependent killing. The data is compatible with a 'pro-receptor' theory for FcR in NK killing, stating that such receptors may function in the same way as the T3 complex interacts with specific T cell receptors.

Antibodies, Monoclonal↗
PubMed1986

Phorbol ester regulation of Ca2+ flux during natural, lectin and antibody-dependent killing.

Phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, suppresses natural, lectin and antibody-dependent killing by normal human lymphocytes in short-term radioisotope release assays. Fifty percent inhibition of killing of lymphoid target cells was seen at approximately 5 ng/ml TPA and inhibition was further potentiated by the presence of monocytic cells. In contrast, TPA increased killing of K-562 erythroleukaemic cells by non-adherent NK cells with optimal activity around 1 ng/ml. Two anti-estrogenic drugs, tamoxifen and clomiphene, known to inhibit protein kinase C, gave near to complete inhibition of NK killing at concentrations 12 microM and 30 microM, respectively. Retinal, another protein kinase C inhibitor, inhibited both antibody-dependent killing and lectin-dependent killing. An influx of 45Ca2+ into the effector population was found during effector-target cell conjugation and this flux was suppressed at TPA concentrations similar to those that suppressed killing. The results suggest that killing depends on a co-ordinated activation of protein kinase C together with a channel-dependent calcium influx. TPA may suppress killing by a negative feedback effect of protein kinase C on the hydrolysis of inositol phospholipids, as demonstrated in many other systems, or through the down-regulation of cell surface receptors required for triggering of lysis.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1985

Products of the lipoxygenase pathway in human natural killer cell cytotoxicity.

As earlier data suggested the importance of lipoxygenase activation for expression of human NK cell cytotoxicity, four different lipoxygenase inhibitors were tested for suppression of natural killer (NK) cell lysis. All inhibitors were found active at nontoxic concentrations with 50% inhibition at approximately 15 microM for nordihydroguaiaretic acid (NDGA). NK cell lysis could be reconstituted to NDGA-suppressed cells with leukotriene B4 (LTB4), the all-trans isomers 6-trans-LTB4 and 12-epi-6-trans-LTB4, and 20-COOH-LTB4. LTB4 reconstitution was best in the concentration range 1-100 pM and near control levels at both higher and lower concentrations. Herpesvirus Ateles-transformed killer T cells could also be inhibited by NDGA. These data indicate that lipoxygenase activity is required for human NK cell lysis and that several different LTB4-related products can restore NK activity in inhibited cells; they also suggest that the lipoxygenase pathway is present in the killer cell population.

Arachidonate Lipoxygenases↗
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

Phorbol ester-induced adhesion (binding) among human mononuclear leukocytes requires extracellular Mg++ and is sensitive to protein kinase C, lipoxygenase, and ATPase inhibitors.

Under gentle shaking, the phorbol 12,13-dibutyrate (P(Bu)2)-induced adhesion among human blood mononuclear leukocytes started within a few minutes, increased with time and was almost complete after 12 h. During this moment and thereafter more than 60% of the cells were in aggregates. Induction of the cell aggregation by 20 min treatment with P(Bu)2 did not occur in Ca++/Mg++-free medium but was almost complete with Mg++ alone and reached its maximal manifestation with both divalent cations present. The intracellular Ca++ antagonist 8-(N,N-diethylamino)octyl-3,4,5-trimethoxybenzoate had a minimal inhibitory effect, and simultaneous treatment of the cells with Ca++ ionophore A23187 and P(Bu)2 did not increase the intercellular binding, whereas A23187 alone induced some cell aggregation. Retinal, a protein kinase C inhibitor, inhibited the intercellular adhesion by more than 50%, and treatment of intact cells with 1-oleoyl-2-acetyl-glycerol, an activator of the enzyme, induced some cell aggregation that was slightly increased when A23187 was added simultaneously. Nordihydroguaiaretic acid, 5,8,11-eicosatriynoic acid and 5,8,11,14-eicosatetraynoic acid, which inhibit lipoxygenation of arachidonic acid, reduced the cell aggregation in contrast to indomethacin and acetylsalicylic acid that had no effect. Cellular ATPases, inhibited by quercetin, but not the ouabain-sensitive Na+, K+-ATPase, appeared to participate, whereas the amiloride-sensitive plasma membrane Na+/H+ exchanger and the intracellular levels of cGMP did not seem to influence the system.

Adenosine Triphosphatases↗
PubMed1985

Second messenger function of arachidonic acid lipoxygenation products in human natural killer cell lysis?

Human natural killer (NK) cells were tested in the presence of several fatty acid oxygenase inhibitors such as nordihydroguaiaretic acid (NDGA), 5,8,11,14-eicosatetraynoic acid, 3-amino-1-m-(trifluoromethyl)-phenyl-2-pyrazoline (BW 755C), and indomethacin. All drugs inhibited NK lysis at the post-target cell-binding level at concentrations that also suppressed lipoxygenation of arachidonic acid, suggesting that such reactivity may be required for effector cell triggering. NDGA gave a 50% NK cell inhibition in the range of 10-30 microM and also suppressed antibody-dependent and lectin-dependent systems. Further evidence of the involvement of arachidonic acid lipoxygenation was found as NK activity could be reconstituted to NDGA-suppressed effector cells with several metabolites such as LTB4, LTB4 analogues, and hydroxyeicosatetraenoic acids lipoxygenated at C-5, C-12, and C-15. Cyclic nucleotides such as cGMP and cAMP could also reconstitute activity with optimal effects at approximately 10(-8) M. The combined evidence is compatible with a model for triggering lysis in which lipoxygenation products have a second messenger function. Whether arachidonic acid lipoxygenation is necessary for effector cells at all different activation/differentiation stages and whether the lipoxygenation products activate guanylic cyclase, protein kinase C, or some other target molecule remain to be further investigated.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗
PubMed1984

Free oxygen radicals are not detectable by chemiluminescence during human natural killer cell cytotoxicity.

Mononuclear cells isolated from peripheral blood of normal donors produce free oxygen radicals (FR), detectable by chemiluminescence (CL), when interacting with target cells during natural killer (NK) cell lysis. FR-producing cells were found to have monocyte characteristics and gave a positive CL reaction when mixed at low concentration (0.5%) with purified NK cells. No correlation was found between susceptibility to NK cell lysis and capacity to induce CL with different target cell lines. Using high and low molecular FR scavengers, no NK cell inhibition was seen with superoxide dismutase, cytochrome c, and catalase, whereas some inhibition was seen with 4,5-dihydroxy-m- benzenedisulphonic acid (Tiron) and 2,3-dihydroxybenzoate. These compounds, however, required higher concentrations than used for inhibition of CL, suggesting an alternative action of these compounds. Normal levels of NK cell activity were found in two patients with chronic granulomatous disease, who were genetically incapable of producing detectable amounts of FR. As a result, it is concluded that human NK cells do not produce large amounts of FR during killing and that FR are unlikely to be the lytic end product. Nevertheless, neither a low degree of FR formation in NK cells nor a more subtle signal-transmitting role of FR during NK cell triggering can be excluded.

1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium ↗
PubMed1984

Effect of 5'-methylthioadenosine, 3-deazaadenosine, and related compounds on human natural killer cell activity. Relation to cyclic AMP and methylation potential.

The effect of 5'-methylthioadenosine (MTA) on human natural killer (NK) cell activity was examined and compared with the effect of 3-deazaadenosine (c3-ado) and periodate-oxidized adenosine (ado-ox). MTA inhibited NK cell activity in concentrations above 30 microM, but in concentrations below 10 microM a slight enhancing effect was often observed. C3-ado and ado-ox were 10 and 3 times more potent, respectively, as inhibitory agents and did not increase NK cell activity in low concentrations. The inhibitory effect of c3-ado was unaffected by preincubation of the cells but was enhanced by the addition of L-homocysteine. In concentrations that caused inhibition of NK cell activity all three agents caused a fall in the methylation index (AdoMet/AdoHcy) but no or an inconsistent effect on the level of cyclic AMP. An increase in the level of AdoHcy was observed already after 1 h of incubation but was more pronounced after 4 h of preincubation with the adenosine derivatives. The inhibition of cytotoxicity was mainly on their initiation of lysis, with a smaller effect on target cell binding. Antibody-dependent cellular cytotoxicity and lectin-dependent cellular cytotoxicity appeared to be less sensitive to inhibition by c3-ado. Our results show that several adenosine analogues inhibit NK-cell-mediated cytotoxicity in parallel with a decreased methylation index. The results suggest that a methylation step is critical in lymphocyte-mediated cytotoxicity and that NK cell activity is more sensitive to inhibition of this step than antibody- or lectin-dependent cytoxicity.

Adenosine↗
PubMed1983

Characterization of insulin binding to the erythroleukemia cell line K 562.

The K 562 is a transformed human erythroid stemcell and is used as a target cell for NK-T-cells. In this study the presence of insulin receptors in K 562 is established. The best binding and negative cooperativity was found in the two Hepes containing buffers whereas no cooperativity was obtained in the Krebs-Ringer buffer. The calculated affinity constants and receptor number per cell varied according to the buffer. Preincubation with insulin caused a down-regulation of the insulin binding capacity. 10 ng/ml caused a lowering of the affinity, with an unchanged number of receptors. 100 ng/ml caused a decrease in receptor number with unchanged affinity. These results were found in both Hepes and Krebs-Ringer phosphate buffer. IGF-I shows cross-reactivity with the insulin receptor, with a potency of 12 and 100 times less than insulin in Krebs-Ringer phosphate buffer and G-buffer respectively. However, no specific IGF-I receptors were found. The presence of receptors on K 562 cells suggests a biological role for insulin. The different results in the different buffers, indicate that a buffer containing Hepes and/or Tris, is required to expose negative cooperativity and make the receptors more accessible to insulin.

Binding, Competitive↗
PubMed1983

Characterization of the phorbol 12,13-dibutyrate (P(Bu)2) induced binding between human lymphocytes.

The mechanisms, cell surface structures, and cell types involved in the phorbol 12,13-dibutyrate (P(Bu)2)-induced binding between human lymphocytes were studied. Induction of cell aggregation by 20 min treatment with P(Bu)2 required Ca2+, an intact membrane, functional microfilaments, and the possible participation of an esterase or, less likely, a protease. Trypsin-sensitive cell surface structures were needed and neuraminidase (NANase) treatment slightly increased the intercellular binding. Retinoic acid, an anti-tumor promoting agent, was inhibitory. Calmodulin-dependent processes, microtubules, phospholipid methylation, intracellular levels of cyclic adenosine monophosphate, and cellular secretion did not seem to be involved. Cell conjugation between 24 hr P(Bu)2-treated and untreated cells required participation of trypsin-sensitive cell surface structures in each of the interacting cells and NANase treatment of one partner slightly increased the intercellular binding. Thymocytes, T cells, mature B and Epstein-Barr virus-transformed B cells aggregated while pre-B, early B, and intermediate B lymphocytes derived from representative malignancies did not. The lack of aggregation was not due to the absence of phorbol ester receptors. It is concluded that the P(Bu2)-induced intercellular binding is mediated by cell surface proteins, depends on certain enzymatic activities and metabolic events and involves certain cell types.

Amino Acids↗