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N Hanna

Publications and source records attributed to N Hanna.

At least 19 recordsLinked to original sources
PubMed1992

Induction of antigen-specific class I-restricted cytotoxic T cells by soluble proteins in vivo.

Cytotoxic T lymphocytes (CTL) are induced specifically against viral and tumor antigens presented by major histocompatibility complex class I molecules on the surface of infected or transformed cells. Intracellular synthesized antigens are processed and associated with class I antigens within cells before presentation on the cell surface. Because of this special requirement for CTL induction, exogenous soluble antigens do not, in general, induce specific CTL responses. To overcome this problem, various laboratories have resorted to the use of vaccinia virus and other replicating expression vectors for intracellular antigen delivery leading to the stimulation of humoral and cell-mediated immunity to specific proteins. However, for human use it is safer to use purified and defined antigens for inducing immune responses. Using soluble ovalbumin and human immunodeficiency virus glycoprotein gp120, we have explored the possibility of using an antigen formulation consisting of squalane and Tween 80 to elicit antigen-specific CTL responses in mice. We have demonstrated that this antigen formulation is a potent inducer of CD8+, class I-restricted, antigen-specific CTLs. The CTL priming induced by soluble antigen in squalane/Tween 80 resembles the reported response to the vaccinia recombinant containing human immunodeficiency virus envelope protein and by splenocytes cytoplasmically loaded with soluble ovalbumin. The ramifications of these findings for vaccine development are discussed.

Adjuvants, Immunologic↗
PubMed1992

Induction of protective class I MHC-restricted CTL in mice by a recombinant influenza vaccine in aluminium hydroxide adjuvant.

Induction of class I MHC-restricted cytotoxic T lymphocyte (CTL) responses by soluble proteins or peptides requires complex adjuvants or carrier systems which are not licensed for use with human vaccines. The data presented in this report show that vaccination with a highly purified recombinant influenza protein antigen in aluminium hydroxide adjuvant, the only adjuvant currently licensed for clinical use, elicited class I restricted CTL and protection from lethal challenge with H1N1 and H2N2 viruses. The antigen (D protein, SK&F 106160) is produced by expression of H1N1 influenza virus-derived cDNA (strain A/PR/8/34) in Escherichia coli, and is composed of the first 81 N-terminal amino acids (aa) of the non-structural protein 1 (NS1) fused via a nine nucleotide non-viral linker sequence to the 157 C-terminal aa of the haemagglutinin 2 subunit (HA2). Previous work by Kuwano et al demonstrated that in vitro stimulation of spleen cells from influenza virus-primed mice, with a partially purified preparation of the D protein, selected for CD8+ CTL clones which facilitated lung clearance of H1N1 and H2N2 viruses. In the current study, these results were extended by studying the responses of mice actively immunized with highly purified D protein in the presence or absence of adjuvants. Vaccination of CB6F1 (H-2dxb) mice with D protein in aluminum hydroxide or Freund's complete adjuvant generated H1N1 cross-reactive, H-2d-restricted, CD8+ CTL directed against an immunodominant HA2 epitope (aa 189-199). D protein without adjuvant did not elicit CTL, regardless of the route of injection. However, long-lived (greater than 6 months) splenic memory CTL were elicited by boosting mice intraperitoneally (i.p.) with the D protein in the absence of adjuvant. In mice injected subcutaneously with D protein in aluminium hydroxide at weeks 0 and 3, survival was increased relative to controls up to 16 weeks beyond the second vaccination, after which time additional boosting was required for protection. Studies in H-2b and H-2k mice vaccinated with the D protein showed that induction of CD4+ T-cell or antibody responses, in the absence of CD8+ CTL, did not correlate with protection. Passive transfer of immune sera from CB6F1 mice was also not protective. This prototype H1N1 recombinant subunit vaccine in aluminium adjuvant should directly address the feasibility of achieving a protective cell-mediated immune response in human influenza.

Adjuvants, Immunologic↗
PubMed1992

"Primatization" of recombinant antibodies for immunotherapy of human diseases: a macaque/human chimeric antibody against human CD4.

Immunoglobulin variable region genes from non-human primates, cynomolgus macaques, were shown to have 85%-98% homology with human immunoglobulin sequences and yet macaques are phylogenetically distant enough to respond against conserved human antigens. Immunoglobulin genes were isolated from monkeys immunized with human CD4 antigen and a human/monkey chimeric anti-CD4 antibody with 91-92% homology to human immunoglobulin framework regions was cloned and expressed. The antibody has an apparent affinity of 3.2 x 10(-11) M and exhibits potent immunosuppressive properties in vitro.

Animals↗
PubMed1991

Pharmacology of the pyrroloimidazole, SK&F 105809--I. Inhibition of inflammatory cytokine production and of 5-lipoxygenase- and cyclooxygenase-mediated metabolism of arachidonic acid.

SK&F 105809 [2-(4- methylsulfinylphenyl)-3-(4-pyridyl)-6,7-dihydro-[5H]-pyrrolo[1,2- a] imidazole] was determined to be a prodrug for the sulfide metabolite SK&F 105561 [2-(4- methylthiophenyl)-3-(4-pyridyl)-6,7-dihydro-[5H]-pyrrolo[1,2-a] imidazole] which inhibited interleukin-1 (IL-1) production in vitro and both 5-lipoxygenase (5-LO) and prostaglandin H (PGH) synthase activities in vitro and ex vivo. SK&F 105561 inhibited partially purified 5-LO with a half-maximal concentration (IC50) of 3 microM. This inhibition was reversible, independent of preincubation time, and dependent on the concentration of the substrate arachidonic acid. SK&F 105561 also inhibited purified PGH synthase with the potency dependent on the level of peroxidase activity. The IC50 was 100 microM in the absence of peroxidase activity, whereas an IC50 of 3 microM was observed in the presence of peroxidase activity. Using human monocytes, SK&F 105561 inhibited A23187-stimulated prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) production with IC50 values of 0.1 and 2 microM, respectively. In addition, IL-1 production by lipopolysaccharide-stimulated human monocytes was also inhibited (IC50 2 microM). Oral administration of SK&F 105809 to rats resulted in a dose-related generation of SK&F 105561 and in the inhibition of thromboxane B2 and LTB4 production ex vivo with a half-maximal dose (ED50) of 15 and 60 mg/kg, respectively. SK&F 105561 showed weak inhibitory activity on 12-lipoxygenase with an IC50 of greater than 200 microM. Neither SK&F 105561 nor SK&F 105809 inhibited the stimulated-turnover of arachidonic acid-containing phospholipids in human monocytes or the activity of cell-free phospholipases A2 and C. Moreover, neither SK&F 105561 nor SK&F 105809 antagonized the binding of LTB4 or leukotriene D4 to membrane receptors. From these results, SK&F 105561, the active principle of SK&F 105809, acts as an inhibitor of both inflammatory cytokine and eicosanoid production.

Animals↗
PubMed1991

Pharmacology of the pyrroloimidazole, SK&F 105809--II. Antiinflammatory activity and inhibition of mediator production in vivo.

SK&F 105809 [2-(4-methylsulfinylphenyl)-3-(4-pyridyl)- 6,7-dihydro-[5H]-pyrrolo[1,2,a] imidazole] demonstrated unique antiinflammatory activities in murine models that are resistant to selective cyclooxygenase (CO) inhibitors. Both edema and inflammatory cell infiltration induced by the topical application of arachidonic acid to the mouse ear were decreased by SK&F 105809 (ED50 values of 44 mg/kg, p.o.). Polymorphonuclear leukocyte (PMN) infiltration following the intraperitoneal injection of either monosodium urate crystal or carrageenan was inhibited with ED50 values of 64 and 72 mg/kg, p.o., respectively. These inflammatory responses were unaffected by the selective cyclooxygenase inhibitor naproxen. SK&F 105809 also inhibited leukotriene B4 (LTB4) and prostaglandin E2 production in vivo in arachidonic acid-induced inflammatory exudates (ED50 values of 41 and 15 mg/kg, p.o., respectively). The inhibition of LTB4 production preceded the inhibition of PMN infiltration. The impact of inhibition of both 5-lipoxygenase (5-LO) and CO was seen with platelet-activating factor-induced vascular permeability which was inhibited markedly by SK&F 105809. However, the 5-LO inhibitor, phenidone, only strongly inhibited when coadministered with the selective CO inhibitor, indomethacin. In spite of a short half-life (14-18 min) for both SK&F 105809 and the active metabolite SK&F 105561 [2-(4- methylthiophenyl)-3-(4-pyridyl)-6,7-dihydro-[5H]-pyrrolo[1,2-a] imidazole], the pharmacological activity lasted at least 1.5 hr. The biochemical evidence of inhibition of interleukin-1 (IL-1) production and 5-LO and CO activity, in vitro, by the metabolite (SK&F 105561) seen in the companion paper (Marshall PJ, Griswold DE, Breton J. Webb EF, Hillegass LM, Sarau HM, Newton J Jr, Lee JC, Bender PE and Hanna N, Pharmacology of the pyrroloimidazole, SK&F 105809--I. Inhibition of inflammatory cytokine production and of 5-lipoxygenase- and cyclooxygenase-mediated metabolism of arachidonic acid. Biochem Pharmacol 42: 813-824, 1991) and inhibition of the fluid and cellular phases of the inflammatory response, in vivo, by SK&F 105809 suggest that this compound possesses a unique profile of activity.

Animals↗
PubMed1991

Activation of the IL-1 gene in UV-irradiated mouse skin: association with inflammatory sequelae and pharmacologic intervention.

The relationship between ultraviolet irradiation, interleukin-1 production, and inflammatory sequelae and the pharmacologic inhibition of these events was investigated in Balb/c mice exposed to ultraviolet irradiation from a bank of six Westinghouse FS40 sunlamps. The resulting edema (66% increase), inflammatory cell infiltration, and rise in the acute-phase reactant (fourfold) serum amyloid P component was preceded by the activation of the interleukin-1 beta gene and enhanced product formation. Administration of dexamethasone, which is known to inhibit interleukin-1 production, inhibited the inflammatory response to ultraviolet irradiation. Thus, production of interleukin-1 may be one of the initial events leading to the consequences of ultraviolet irradiation exposure.

Animals↗
PubMed1990

Differential inhibition of histamine release from mast cells by protein kinase C inhibitors: staurosporine and K-252a.

Pretreatment of rat peritoneal mast cells with either staurosporine or an analog K-252a [(8R*,9S*,11S*)-(-)-9-hydroxyl-9-methoxycarbonyl-8-methyl-2,3, 9,10-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b,11-atrizadibenzo- [a,g]cycloocta[cde]trinden-1-one] led to a concentration-related inhibition of histamine release when the cells were stimulated with anti-IgE (IC50: staurosporine = 110 nM; K-252a = 100 nM). In contrast, the two protein kinase C (PKC) inhibitors (1-1000 nM) partially (less than 15%) inhibited histamine release induced by compound 48/80 (0.5 to 1 micrograms/mL). Furthermore, prostaglandin E2 (PGE2) synthesis mediated by anti-IgE from rat peritoneal mast cells was also inhibited by staurosporine and K-252a (IC50 = 100 nM). Exposure of anti-arsenate IgE (anti-Ars-IgE) sensitized mouse bone marrow derived mast cells to arsenate-bovine serum albumin (Ars-BSA) led to the release of both histamine (510 +/- 12.6 ng/10(6) cells) and immunoreactive leukotriene C4 (LTC4) (27.0 +/- 2.6 ng/10(6) cells). Both histamine and LTC4 release was inhibited by staurosporine and K-252a with an IC50 of 50 nM for both compounds. We also characterized a 45K molecular weight protein which is phosphorylated by PKC after Ars-BSA or phorbol, 12-myristate, 13-acetate (PMA) stimulation. This protein is phosphorylated in a broken cell preparation in which PKC is activated by phosphatidylserine/Diolein and Ca2+. Peptide mapping by V8 protease of the phosphorylated 45K protein revealed that the 45K protein phosphorylation patterns induced by IgE or PMA or in the broken cell preparation are identical. Pretreatment of 32P-labeled mouse bone marrow derived mast cells with either staurosporine or K-252a led to a concentration-related inhibition of 45K protein phosphorylation induced by PMA or Ars-BSA. This inhibition of protein phosphorylation correlated well with the inhibition of histamine and leukotriene release in bone marrow derived mast cells.

Alkaloids↗
PubMed1990

Potentiation of topoisomerase inhibitor-induced DNA strand breakage and cytotoxicity by tumor necrosis factor: enhancement of topoisomerase activity as a mechanism of potentiation.

A combination of tumor necrosis factor (TNF) and the topoisomerase I inhibitor, camptothecin, or the topoisomerase II inhibitors, teniposide and amsacrine, produced dose-dependent synergistic cytotoxicity against the murine L929 fibrosarcoma cells. Similar synergy was not observed with a combination of TNF and bleomycin. To define the role of TNF in the augmentation of tumor cell killing by topoisomerase I or II inhibitors, the effect of TNF on the production of enzyme-linked DNA strand breaks induced in cells by topoisomerase inhibitors was investigated. L929 cells incubated for 1 h with the topoisomerase inhibitors contained protein-linked strand breaks. In contrast, TNF alone did not induce DNA strand breakage. However, when cells were incubated simultaneously with TNF and camptothecin, amsacrine, Adriamycin, actinomycin D, teniposide, or etoposide, increased numbers of strand breaks were produced. Preincubation of the cells with TNF for 30 min or 3 h before the addition of camptothecin or etoposide resulted in no more strand breaks than that observed in cells incubated with the drugs alone. TNF treatment of L929 cells produced a rapid and transient increase in specific activity of extractable topoisomerases I and II. These increases were maximum at 2-5 min of TNF treatment and by 30 min the activities of extractable enzymes were equal to or less than those detected in extracts from untreated cell controls. The transient nature of the increase in extractable topoisomerase activity may explain the kinetics and significance of the order of addition of TNF and inhibitors for maximal synergistic activity. These data are consistent also with a role for topoisomerase-linked DNA lesions in the TNF-mediated potentiation of killing of L929 cells by topoisomerase inhibitors.

Amsacrine↗
PubMed1990

Humoral response of cynomolgus macaques to human soluble CD4: antibody reactivity restricted to xeno-human determinants.

The CD4 cell surface glycoprotein which is expressed primarily by a subset of T lymphocytes plays a key role in normal immune responses. In the immunopathogenesis of AIDS, it serves as the high-affinity receptor for HIV, facilitating viral attachment and entry into CD4+ cells. As such, the truncated soluble form of this molecule (sT4) has been proposed as a therapeutic drug for the treatment of AIDS whereby it would act as decoy for viral entry into cells or facilitate elimination of soluble viral envelope glycoprotein. In a study designed to look at the effect of sT4 on immune function, sT4 was administrated to experimentally naive primates. In this report, we show that administration of sT4 to cynomolgus macaque monkeys over a period of up to 3 weeks results in antibody responses with specificities for human CD4 molecules. Antisera thus generated bound sT4 and cell surface CD4 expressed on human T lymphocytes but failed to bind to cynomolgus lymphocytes. These antibodies caused no apparent adverse effects on normal immune functions of the cynomolgus macaques. We conclude from these data that the antibody response to soluble CD4 in cynomolgus monkeys is directed at determinants present on human CD4 but absent on monkey CD4. The restricted xenogeneic specificity of the antibody response indicates that soluble CD4 may not be highly immunogenic in syngeneic hosts. The present study also shows that these antibodies can block HIV-induced syncytium formation indicating that the antibodies bind to regions on the CD4 molecule close to the HIV-env gp120 binding site. The gp120 binding site, which resides within the N-terminal V1 domain of CD4, encompasses a region which corresponds to the complementarity determining regions (CDRs) of immunoglobulins. The CDR-like regions of CD4-V1 manifest the greatest species divergence, are tolerant to experimental in vitro mutagenesis, and generate the predominant antibody response in mice immunized with human CD4 indicating that differences in the V1 sequence between human and other non-human primates may localize to this regions.

Animals↗
PubMed1990

Hypotension induced by vasopressin antagonists in rats: role of mast cell degranulation.

SK&F 101926, a synthetic peptide, is a potent antagonist of vasopressin at both the V2 and the V1 receptors. Following intravenous administration of SK&F 101926 (5 mg/kg), mean arterial pressure (MAP) immediately fell 75 mm Hg. Heart rate increased approximately 50 beats/min. Cutaneous flushing and cyanosis appeared approximately 2 to 5 min after the SK&F 101926 administration. Three of the five rats died within 40 min with no improvement in either color or MAP. The two surviving animals slowly recovered from these symptoms. The hypotension and flushing recorded in these studies resembled the effects during hypotensive shock. SK&F 101926 degranulated rat peritoneal mast cells in vitro as measured by the liberation of histamine. Analogs of SK&F 101926 were identified having reduced activity to release histamine from mast cells in vitro. The activity of these analogs to release histamine in vivo was also tested, as reflected by rat paw edema. A positive correlation was found between the potency to produce edema in vivo and the potency to release mast cell histamine in vitro (r = 0.94, p less than 0.05). In addition, compounds that released mast cell histamine and induced rat paw edema also produced hypotension and death when administered intravenously, while analogs which produced minimal histamine release in vitro produced minimal or no cardiovascular changes or lethality in vivo at the same dosages (5 mg/kg). Finally, cyproheptadine (10 mg/kg), an antagonist at both the serotonin and the histamine receptors, blunted the effects of SK&F 101926 on MAP and blocked the lethality. Pretreatment with a combination of histamine (H1 and H2) antagonists provided little protection against the SK&F 101926-induced toxicity. These data indicate that the cardiovascular toxicity of SK&F 101926 (and related peptides) is mediated via the release of autocoids from mast cells. Serotonin appears to play a major role in mediating the cardiovascular toxicity of SK&F 101926.

Animals↗
PubMed1990

Induction of non-specific suppressor cells in normal Lewis rats by a novel azaspirane SK&F 105685.

SK&F 105685 (N,N-Dimethyl-8,8-dipropyl-2-azaspiro[4,5]decane-2- propanamine dihydrochloride) is a novel azaspirane which has therapeutic activity in rat models of autoimmune disease. In this study, we have demonstrated that SK&F 105685 is a potent inducer of non-specific suppressor cells (SC). Oral administration of 15-30 mg/kg/day results in the generation of SC in the spleen, lymph nodes and bone marrow, but not the thymus of Lewis rats. Splenic SC suppress Con-A-induced proliferation in co-culture assays at effector-responder ratios of 1:1 to 1:64. SC are radiation resistant (2000 R), non-T, non-B cells, partially adherent to plastic surfaces and are enriched in a 1.07 g/ml fraction of a Percoll density gradient. Their activity is increased, rather than ablated, by indomethacin. No definitive changes in Ig+, OX-19+, OX-8+, W3/25+ or asialo GM1+ cells could be detected in the spleens of treated rats compared to control untreated animals. Elevated levels of both radiation-sensitive and radiation-resistant suppressor cells were found in the bone marrow of treated rats in addition to the radiosensitive SC normally present in this tissue.

Adjuvants, Immunologic↗
PubMed1990

Antiarthritic and suppressor cell inducing activity of azaspiranes: structure-function relationships of a novel class of immunomodulatory agents.

Spirogermanium (1; 8,8-diethyl-N,N-dimethyl-2-aza-8- germaspiro[4.5]decane-2-propanamine dihydrochloride) is a potent cytotoxic agent in vitro which has demonstrated limited activity in experimental animal tumor models. Subsequently, it has been reported that spirogermanium has antiarthritic and suppressor cell-inducing activity. We have synthesized a series of substituted 8-hetero-2-azaspiro[4.5]decane and 9-hetero-3-azaspiro[5.5]undecane analogues of spirogermanium to identify the heteroatom requirements for in vivo antiarthritic and suppressor cell-inducing activity. This structure-activity relationship study has identified that appropriately substituted silicon and carbon analogues of spirogermanium retain both antiarthritic and immunosuppressive activity, with the 8,8-dipropyl (carbon) analogue being among the most active. Following the identification of N,N-dimethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine++ + dihydrochloride (9) as a more active analogue than spirogermanium, a series of 8,8-dipropyl analogues with various amine substituents were synthesized. A number of these analogues had activity similar to that of 9. A correlation between activity in the adjuvant arthritic rat and the ability to induce suppressor cells (r = 0.894, p less than 0.001) suggests an association between the two pharmacologic effects. While the precise biochemical mechanism(s) for the pharmacological activity is unclear, these data suggest that compounds within this series, e.g., N,N-dimethyl-8,8-dipropyl-2-azaspiro[4.5]decane-2-propanamine++ + dihydrochloride, may provide effective therapy in diseases of autoimmune origin and/or the prevention of rejection in tissue transplantation.

Animals↗
PubMed1990

Pharmacological profile of SK&F 105809, a dual inhibitor of arachidonic acid metabolism.

The effects of SK&F 105809, 6,7,-dihydro-2-[4(methylsulfinyl) phenyl]-3-(4-pyridyl) -5[H]-pyrrolo[1,2-a] imidazole, on eicosanoid metabolism, inflammatory responses, algesia and ulcer formation are described. SK&F 105809 was determined to be a prodrug for the sulfide metabolite SK&F 105561 which is an inhibitor of 5-lipoxygenase (5-LO) and prostaglandin H (PGH) synthase activities seen with both the isolated enzyme (IC50S 3 microM) and human monocyte production of the eicosanoids leukotriene B4 (LTB4, IC50 1.0 microM) and prostaglandin E2 (PGE2, IC50 0.1 microM). In-vivo conversion of SK&F 105809 to the active principle SK&F 105561 was observed in both mice and rats. SK&F 105809 inhibited LTB4 and PGE2 production in vivo in inflammatory exudates as well as the production of LTB4 and thromboxane B2 (TxB2) ex vivo in rat blood. SK&F 105809 inhibited oedema and inflammatory-cell infiltration in arachidonic acid-induced inflammation in the mouse ear and rat paw as well as in carrageenan- and monosodium urate crystal-induced peritonitis. SK&F 105809 was also effective in inhibiting mouse collagen-induced arthritis and associated acute-phase reactant protein. At the same time, these acute and chronic models of inflammation were found to be resistant to the action of selective cyclooxygenase inhibitors such as naproxen. In addition, SK&F 105809 possessed analgesic activity in phenylquinone-induced abdominal constriction assay and inhibited indomethacin-induced ulcers.

Administration, Oral↗
PubMed1989

Structural analysis of the human immunodeficiency virus-binding domain of CD4. Epitope mapping with site-directed mutants and anti-idiotypes.

The CD4 molecule, a differentiation marker expressed primarily by T lymphocytes, plays an important role in lymphocyte activation. CD4 is also the receptor for HIV. A number of recent studies have localized the high affinity binding site of the HIV envelope glycoprotein, gp120, to the NH2-terminal (V1) domain of CD4, a region with sequence and predicted structural homology with Ig kappa chain V domains (V kappa). In this report, we show that V1 bears structural similarities with V kappa regions through detailed epitope mapping of 26 CD4 mAbs. The binding sites of these mAbs were initially defined relative to one another by crossblocking analysis and were then localized to specific domains of CD4 in blocking studies with truncated, soluble CD4 proteins. The epitopes within the V1 domain were mapped in detail with a panel of 17 substitution mutants, and the specificities of several mAbs that appear to recognize very similar epitopes were examined in crossblocking studies with anti-idiotype antibodies. The location of the epitopes is consistent with a V kappa-like structure of V1. Most of the epitopes lie within regions of predicted exposed loops. A number of these epitopes span discontinuous residues in the linear sequence that lies in close proximity in an Ig fold. Alignment of CD4 V1 with the Ig V kappa chains places these epitopes within stretches corresponding to the complimentarity-determining regions. This epitope analysis is relevant for a vaccine strategy for HIV based on anti-idiotype antibodies to CD4 mAbs and for studies with CD4 antibodies on the role of CD4 in T lymphocyte activation.

Amino Acid Sequence↗
PubMed1989

Synergistic antitumor effects of topoisomerase inhibitors and natural cell-mediated cytotoxicity.

The mechanism of augmentation of tumor cell killing by immune effector cells and chemotherapeutic drugs was studied. The effect of treating tumor cells with various antineoplastic drugs on their sensitivity to murine natural cell-mediated cytotoxicity in vitro was investigated. Pretreatment with actinomycin D at nontoxic concentrations rendered L929 and WEHI-164 tumor cells more susceptible to killing by mouse spleen lymphocytes in a dose-dependent manner. Similarly, enhancement of L929 tumor cell killing by natural cell-mediated cytotoxicity was observed following treatment of the target cells with the topoisomerase II inhibitors, Adriamycin, amsacrine, bisantrene, etoposide, and teniposide, as well as with topoisomerase I inhibitor, camptothecin. In contrast, drugs which induce their cytotoxic effects by mechanisms that do not involve topoisomerase inhibition such as bleomycin, vinblastine, vincristine, and mitomycin C failed to exhibit synergism with natural cell-mediated cytotoxicity. However, moderate synergy was consistently observed with cis-platinum. The effector cells responsible for the cytotoxicity in the present system are natural cytotoxic cells since they kill WEHI-164 but not YAC cells, are resistant to treatment with anti-asialo-GM1 antibody, and their activity is abolished by anti-tumor necrosis factor antibodies. Indeed, tumor necrosis factor-mediated cytotoxicity of WEHI-164 or L929 was enhanced by treatment of the target cells with topoisomerase II inhibitors. Moreover, WEHI-164 cells selected for tumor necrosis factor resistance were resistant to natural cell-mediated cytotoxicity, and no synergy could be observed with topoisomerase inhibitors.

Animals↗
PubMed1989

Inhibition of inflammatory cell infiltration by bicyclic imidazoles, SK&F 86002 and SK&F 104493.

The mode of action of the dual inhibitors of eicosanoid metabolism, SK&F 86002 and SK&F 104493 was evaluated on inflammatory cell infiltration induced in mice by carrageenan, monosodium urate crystals, and arachidonic acid. The results were compared to those seen with standard antiinflammatory compounds. Inflammatory cell infiltration was inhibited by SK&F 86002. SK&F 104493, colchicine, and phenidone but not naproxen. In vivo, PMN infiltration induced by LTB4 was inhibited by colchicine but not by SK&F 86002, SK&F 104493, or phenidone treatment. Similarly, in vitro chemotaxis to LTB4 was not inhibited by SK&F 86002. The 5-lipoxygenase inhibitors, SK&F 86002, SK&F 104493, and phenidone inhibited LTB4 production in vivo as well as inflammatory cell infiltration induced by arachidonic acid. The data are consistent with the suggestion that the bicyclic imidazoles inhibit PMN infiltration by virtue of inhibition of LTB4 production.

Animals↗
PubMed1989

Effects of prostaglandins and cAMP levels on monocyte IL-1 production.

The effects of prostaglandin E2 (PGE2), as well as other cAMP-elevating agents, on the in vitro production of interleukin-1 (IL-1) by human monocytes (HM) were examined. Exposure to E. coli lipopolysacharide (LPS) resulted in a dose- and time-dependent increase of IL-1 activity in monocytes culture supernatants. Maximal levels of secreted IL-1 in response to 10 ng LPS/ml were obtained at 18 h. PGE1, PGE2, cholera toxin (CT) and the phosphodiesterase inhibitor, isobutylmethylxanthin (IBMX), when added with LPS, resulted in a dose-dependent increase in cellular cAMP and in secreted IL-1. Maximal levels of secreted IL-1 were 2.5-5.0-fold over LPS alone. When CT or PGE2 was added with IBMX a further increase was observed. These agents exhibited marginal effect on cell-associated IL-1. Maximum cAMP levels was achieved at 10 min in response to either PGE1 or PGE2 and returned to near basal levels after 18 h. While PGE1 elevated cAMP to a larger extent than PGE2 (58- vs. 30-fold) the latter resulted in a higher levels of secreted IL-1. Elevated cAMP persisted throughout the entire culture period in response to CT (4-6-fold) or IBMX (7-fold). Thus, we conclude that in adherent HM, IL-1 production is potentiated and not inhibited by prostaglandins or agents that elevate cellular cAMP.

1-Methyl-3-isobutylxanthine↗