PubMed Health⌕ Search

Biomedical subjects

J W Larrick

Publications and source records attributed to J W Larrick.

At least 109 records · Page 6Linked to original sources
PubMed1987

Enhancement of neutrophil superoxide production by preincubation with recombinant human tumor necrosis factor.

Tumor necrosis factor (TNF) is a 17,000-Da protein which is produced by mononuclear cells upon exposure to endotoxin. Increases in adherence, phagocytosis, hydrogen peroxide release, and lysozyme secretion have been demonstrated after prolonged incubation of human neutrophils with TNF. In this study, the ability of highly purified recombinant human TNF to modulate neutrophil responses to soluble stimuli was evaluated. Tumor necrosis factor alone (0.1 to 10,000 units/ml) failed to induce neutrophil superoxide anion (O2-) production, granule release, or aggregation when incubated for up to 25 min at 37 degrees C. TNF did, however, stimulate a significant time-, dose-, and temperature-dependent increase in neutrophil F-actin content. Although exposure of neutrophils to TNF alone caused no superoxide anion production, it enhanced the O2- production in response to the chemotactic peptide, f-methionyl-leucyl-phenylalanine (FMLP) or the tumor promotor, phorbol myristate acetate, by as much as 278%. The enhancement was time-, dose-, and temperature-dependent and was due to a more rapid initial rate of O2- production. The TNF enhancement of FMLP-induced O2- production was blocked when an anti-TNF monoclonal antibody 241-1H11, is present during the preincubation period. TNF preincubation also enhanced FMLP-induced lysozyme release, but had no effect on aggregation and actin polymerization by FMLP. The kinetics of NADPH oxidase activation by arachidonic acid was unaltered by TNF. These results indicate that brief exposures to recombinant human TNF are able to enhance or prime the neutrophil oxidative burst in response to a second stimulus.

Actins↗
PubMed1987

Stimulation of prostaglandin E2 and thromboxane B2 production by human monocytes in response to interleukin-2.

Interleukin 2 (IL-2) is a potent lymphokine involved in the regulation of immune responses and is classically regarded as a stimulus for the activation and growth of T-cells. Recent reports have demonstrated the IL-2 dependent activation of human peripheral blood lymphocytes into lymphokine activated killer cells capable of lysing tumor cells both in vitro and in vivo. In this study we report data which clearly show IL-2 may also act to down-regulate the immune response by inducing the synthesis of arachidonic acid metabolites with known immunosuppressive actions. Stimulation of peripheral human blood monocytes with IL-2 caused an increased production of prostaglandin E2 (PGE2) and thromboxane (TXB2) in a dose-dependent manner. Kinetic analysis showed no increase above controls after 6 hours and maximal levels by 10 hours; elevated levels were maintained after 45 hours of incubation. After 20 hours of stimulation with 2000 U/ml IL-2, the level of PGE2 and TXB2 were greater than three-fold above controls, 0.7 and 19 ng/10(6) cells, respectively. The stimulation was relatively specific in that neither prostacyclin nor leukotrienes were produced in response to IL-2. These data demonstrate that IL-2 acts on human monocytes to induce the secretion of PGE2 and TXB2.

6-Ketoprostaglandin F1 alpha↗
PubMed1987

Murine monoclonal antibodies defining neutralizing epitopes on tumor necrosis factor.

A panel of four monoclonal antibodies (MAbs) was generated against recombinant human tumor necrosis factor-alpha (rTNF). These MAbs immunoprecipitate 125I-labeled rTNF, block binding of 125I-labeled rTNF to L929 mouse fibroblasts, and neutralize in vitro cytotoxicity of rTNF and native TNF (nTNF) in the L929 cytotoxicity assay. They define distinct epitopes closely associated with the receptor binding site of rTNF. In Western analysis they bind to both monomeric and dimeric rTNF. Two MAbs recognizing distinct epitopes were used to develop a 'sandwich' enzyme immunometric assay (EIMA) to measure rTNF levels in human serum and other fluids.

Animals↗
PubMed1987

Antibiotic therapy, endotoxin concentration in cerebrospinal fluid, and brain edema in experimental Escherichia coli meningitis in rabbits.

We investigated the effect of cefotaxime and chloramphenicol on endotoxin concentrations in cerebrospinal fluid (CSF) and on the development of brain edema in rabbits with Escherichia coli meningitis. Both antibiotics were similarly effective in reducing bacterial titers. Cefotaxime, but not chloramphenicol, induced a marked increase of endotoxin in CSF, from log10 1.5 +/- 0.8 to log10 2.8 +/- 0.7 ng/ml (P less than .01). This result was associated with an increase in brain water content (405 +/- 12 g of water/100 g of dry weight compared with 389 +/- 8 g in untreated controls; P less than .01), whereas in animals treated with chloramphenicol, brain water content was identical to controls. The cefotaxime-induced increase in endotoxin concentration and brain edema were both neutralized by polymyxin B, which binds to the lipid A moiety of endotoxin, or by a monoclonal antibody to lipid A. These results indicate that treating gram-negative bacillary meningitis with selected antibiotics induces increased endotoxin concentrations in CSF that are associated with brain edema.

Animals↗
PubMed1987

Characterization of murine monoclonal antibodies that recognize neutralizing epitopes on human C5a.

We generated a panel of 10 murine monoclonal antibodies (MAbs) that recognize human complement fragment C5a. These MAbs were characterized for their ability to immunoprecipitate 125I-labeled C5a, bind C5a in solid-phase enzyme immunoassay, and block 125I-labeled C5a binding to polymorphonuclear leukocytes. Four of these MAbs had affinity constants for C5a in the 1 X 10(9) to 3 X 10(9) M-1 range. These MAbs blocked C5a-induced neutrophil polarization and chemiluminescence. They blocked the ability of passively administered C5a to cause neutropenia in rabbits. These anti-C5a neutralizing MAbs may have potential therapeutic use in states of complement activation.

Antibodies, Monoclonal↗
PubMed1987

Human monoclonal antibodies that recognize conserved epitopes in the core-lipid A region of lipopolysaccharides.

Epstein-Barr virus (EBV)-transformed human B lymphocytes were fused with a murine-human heteromyeloma to produce stable hybrid cell lines that secreted human monoclonal antibodies (mAbs) of the IgM class that recognized conserved epitopes in the core-lipid A region of lipopolysaccharides (LPS). Three of the mAbs reacted with epitopes on the lipid A moiety, while a fourth recognized a determinant in the core oligosaccharide. The lipid A-specific mAbs cross-reacted with heterologous rough LPS and with lipid As released by acid hydrolysis of different intact (smooth) LPS. Carbohydrate groups in the O-side chain and core oligosaccharide of isolated, smooth LPS restricted antibody access to antigenic sites on lipid A. Yet, one lipid A-reactive mAb recognized its epitope on the surfaces of a variety of intact bacteria. These findings confirm the presence of highly conserved epitopes in the core-lipid A complex and prove the existence of human B cell clones with the potential for secreting high avidity IgM antibodies that react with these widely shared determinants. Such human mAbs might provide protective activity against disease caused by diverse gram-negative bacteria.

Animals↗
PubMed1987

Receptor-mediated monocytoid differentiation of human promyelocytic cells by tumor necrosis factor: synergistic actions with interferon-gamma and 1,25-dihydroxyvitamin D3.

Human myeloid leukemia cells respond to various signals by differentiating to more mature cells. This study was designed to evaluate the effects of a mononuclear phagocyte-derived factor, tumor necrosis factor/cachectin (TNF), on the proliferation and differentiation of the human cell lines HL-60 (promyelocytic) and U937 (monoblastic), and to characterize TNF receptors on these cells. TNF had no effect on HL-60 cell growth or thymidine incorporation, but it markedly inhibited that of U937 cells. HL-60 cells treated with TNF formed osteoclast-like polykaryons and developed nonspecific esterase positivity. In a dose-dependent fashion, TNF enhanced HL-60 cell nonspecific esterase activity, H2O2 production, NBT reduction, and acid phosphatase content. Together, TNF and interferon-gamma (IFN-gamma) additively and synergistically caused increases in these activities as well as the expression of HLA-DR and the monocyte antigens LeuM3 (CDw14) and OKM1 (CD11). TNF also synergistically enhanced the differentiating effects of 1,25-dihydroxyvitamin D3. The potentiating actions of D3 of IFN-gamma on the TNF effect were maximal when the two agents were present together throughout the incubation, and pretreatment with TNF augmented the subsequent response to D3, but not IFN-gamma. HL-60 and U937 cells bound 125I-labeled TNF specifically, rapidly, and reversibly with binding constants of 227 and 333 pmol/L and receptors per cell of 4,435 and 6,806 for HL-60 and U937, respectively. Scatchard plots were linear, which suggested single classes of receptors. HL-60 TNF receptors were not changed by a three-day treatment with IFN-gamma or D3. U937 and HL-60 cells internalized and degraded 125I-labeled TNF to comparable degrees. TNF has differing effects on HL-60 and U937 cells that are apparently mediated through comparable high-affinity TNF receptors. The unique responses of different cell types to TNF may be due to postreceptor factors.

Antigens, Surface↗
PubMed1987

Acute in vivo effects of human recombinant tumor necrosis factor.

Tumor necrosis factor is a peptide cytokine that induces hemorrhagic necrosis of some tumors and is responsible for the severe cachexia observed in advanced infectious diseases. We evaluated the acute effects of intravenous administration of purified human recombinant tumor necrosis factor in mice. With as little as 0.01 microgram/mouse (0.00045 mg/kg) a peripheral blood lymphopenia and neutrophilia developed as determined by flow cytometric analysis. At 1 microgram/mouse, the lymphopenia was both relative (21 +/- 3% versus 65 +/- 3%; p less than 0.001 treated versus control) and absolute (62 +/- 10 versus 229 +/- 29 X 10(4) cells/ml p less than 0.001). The neutrophilia was also relative (79 +/- 3% versus 34 +/- 3%; p less than 0.001 treated versus control) and absolute (237 +/- 26 versus 110 +/- 13 X 10(4) cell/ml; p less than 0.001). The neutrophilia was due to an increase in both mature and immature cells. At the higher doses the animals developed hypovolemic shock with an increased hematocrit and watery diarrhea occurred. Microscopic examination of the small bowel disclosed necrosis of the villi. Ultrastructural studies of the small bowel confirmed the necrosis and also showed severe endothelial cell damage, pyknotic nuclei, exocytosis of Paneth cell granules, and extravasation of red blood cells and neutrophils into the interstitium. A vascular leak syndrome developed with preferential fluid loss into the small and large bowel. These data demonstrate the potent in vivo effects of purified human recombinant tumor necrosis factor.

Animals↗
PubMed1987

Recombinant tumor necrosis factor causes activation of human granulocytes.

We have tested the hypothesis that tumor necrosis factor (TNF), by binding to and activating granulocytes, may contribute to the pathogenesis of gram-negative sepsis and the adult respiratory distress syndrome (ARDS). Buffy coat granulocytes incubated with as little as 0.5 ng/mL of recombinant TNF (rTNF) showed a dose-related increase in nitroblue tetrazolium dye reduction, in granulocyte polarization, in superoxide anion release, and in visually apparent aggregation. Purified lipopolysaccharide (1 microgram/mL) caused polymorphonuclear (PMN) aggregation and activation that was neutralized by polymyxin B. The release of superoxide was augmented by preincubation of the PMNs with gamma-interferon. The effect of TNF was neutralized by TNF-specific murine monoclonal antibodies but not by polymyxin B. Scatchard analysis of 125I-rTNF binding to granulocytes revealed about 1,200 receptors per cell with a Kd of 4.9 X 10(-10) mol/L. These results suggest that the release of TNF by mononuclear phagocytes contributes to granulocyte activation and aggregation during inflammation.

Glycoproteins↗
PubMed1986

Is Reye's syndrome caused by augmented release of tumour necrosis factor?

Reye's syndrome affects children with a history of viral infection treated with aspirin. Its pathogenesis is unclear. Tumour necrosis factor (TNF) is released by macrophages activated by viral infection, endotoxin, and phagocytosis, and it has been shown to be a mediator of the toxic and metabolic effects of endotoxaemia. The metabolic effects of endotoxin and TNF are similar to those found in Reye's syndrome. Raised levels of TNF are released from macrophages treated with non-steroidal anti-inflammatory drugs, and young animals are known to be more sensitive than mature animals to both TNF and endotoxin. These observations lead to the hypothesis that an increased release of TNF in selected young patients treated with aspirin contributes to the development of Reye's syndrome.

Animals↗
PubMed1986

Tumor necrosis factor stimulates interleukin-1 and prostaglandin E2 production in resting macrophages.

We have investigated the effect of tumor necrosis factor on the release of interleukin-1 and PGE2 from murine resident peritoneal macrophages. Tumor necrosis factor causes an increase in the production of interleukin-1 and PGE2 with a maximum induction for both noted at 5.9 X 10(-8) M. While indomethacin decreased tumor necrosis factor induced PGE2 production, this cyclooxygenase inhibitor augmented tumor necrosis factor induced interleukin-1 production. Our data suggests that tumor necrosis factor may be an important immunopotentiating agent in addition to its previously described cytolytic and metabolic activities.

Animals↗
PubMed1986

Association of systemic immune complexes, complement activation, and antibodies to Pseudomonas aeruginosa lipopolysaccharide and exotoxin A with mortality in cystic fibrosis.

The relevance of circulating immune complexes, plasma complement activation, and serum antibodies against discrete antigens of Pseudomonas aeruginosa, to the clinical course in patients with cystic fibrosis (CF) is unknown. We related these factors to outcome in 49 patients with CF colonized by P. aeruginosa, comparing 14 who died of lung disease with 35 survivors of similar age and duration of colonization, as well as 9 uncolonized patients with CF, 24 patients with other bronchorrheic lung disease, and 10 healthy control subjects. The patients with CF colonized by P. aeruginosa who died had a higher incidence of immune complexes than did survivors (71 versus 40%, p less than 0.05). Moreover, C4 activation was highly associated with immune complexes and mortality (p less than 0.001 for each). Those who died also had much higher levels of IgG antibodies to P. aeruginosa lipopolysaccharide (LPS) and exotoxin A than did survivors colonized by P. aeruginosa (p less than 0.005 and p = 0.01, respectively), whereas both groups had similar levels of P. aeruginosa sonicate, elastase, alkaline protease, and endotoxin core antibodies. We conclude that increasing levels of serum IgG antibodies to P. aeruginosa LPS and exotoxin A and the presence of systemic immune complexes and complement activation are associated with poor prognosis in CF, and may provide useful noninvasive markers for studying the possible immunopathogenesis of CF lung disease.

Adolescent↗
PubMed1986

Selective inhibition of the growth of human erythroid bursts by monoclonal antibodies against transferrin or the transferrin receptor.

The relative requirements of colonies derived from erythroid (BFU-E) and myeloid (CFU-c) progenitors for transferrin were examined using monoclonal antibodies directed against the transferrin molecule (TF-6) or its cell surface receptor (TFR-A12, TFR1-2B). Growth of erythroid bursts was profoundly reduced at concentrations of all three antibodies that had no effect on CFU-c-derived colonies. When TFR1-2B was layered over cultures established one to seven days previously, further burst development was inhibited, and degeneration of early erythroid colonies was observed. Addition of erythropoietin augmented transferrin receptor expression on cells harvested after 1 to 2 weeks in culture and analyzed by flow cytometry. Recombinant human erythropoietin gave results comparable to those obtained in experiments using human urinary erythropoietin. Analysis of erythroblasts plucked directly from culture plates confirmed the presence of transferrin receptors on BFU-E-derived colonies. Thymidine incorporation was maximal early in the second week of culture and coincided with high transferrin receptor expression. These data demonstrate that transferrin must be available into the second week of culture to support the growth and differentiation of BFU-E-derived erythroid bursts, that the generation of erythroid colonies from BFU-E is more dependent on transferrin than myeloid colony formation from CFU-c, and that erythropoietin modulates the expression of transferrin receptors on growing bursts.

Antibodies, Monoclonal↗
PubMed1986

Prospects for the therapeutic use of human monoclonal antibodies.

Despite much recent progress, human monoclonal antibodies (HuMAbs) are currently more difficult to generate than conventional rodent monoclonals. Clinical trials using rodent monoclonals suggest that they can be given safely, but that the human antimouse immune response can limit their efficacy. We review the human monoclonals that have been generated to date, and explore the clinical uses that will be made of these reagents in the near future.

Animals↗
PubMed1985

An improved assay for the detection of interleukin 1.

A 24 h, highly sensitive assay for detection of interleukin 1 (IL-1) is described. A thioguanine-resistant mutant of the murine lymphoma cell line LBRM 33 was selected (LBRM TG6). When this cell line was incubated with low concentrations of PHA and IL-1 it produced interleukin 2 (IL-2). IL-2-dependent HT2 cells were co-cultured with the LBRM cells to measure the released IL-2. Prior to addition of tritiated thymidine to the co-culture, hypoxanthine and azaserine were added to metabolically block DNA synthesis by LBRM TG6 cells. This resulted in a sensitive, short term assay requiring minimal technical manipulations and characterized by a high signal to noise ratio.

Animals↗
PubMed1985

Markers of genetic variation among the Waorani Indians of the Ecuadorian Amazon headwaters.

Until recently, the Waorani Indians of Ecuador's Amazon headwaters maintained a fierce resistance to all intruders into their territory, and as a result of their actions and reputations a population of 600 people controlled a very large territory (about 8,000 square miles). The isolation of the Waorani has resulted in a large linguistic and genetic distance from their neighbors. Our survey of red cell enzymes, immunoglobulin allotypes, and dermatoglyphics demonstrates that the Waorani are a highly inbred and homogeneous population. Of 18 red cell enzymes studied, the Waorani have a limited polymorphism for only 6. Only two Gm haplotypes (Gm1,2,17,21, Gm1,17,21) were found and 60% of those tested were homozygous for the Gm1,17,21 haplotype. All individuals were A2m (1) and 95% of these were homozygous. The Waorani's dermatoglyphic traits fell within the wide range found among other South American Indians with close affinity to the Ecuadorian Jivaro group. Despite the limitations of these genetic systems, they demonstrate that the Waorani share limited genetic traits with the neighboring Jivaro Indians and are isolated from other tribal populations in South America.

Dermatoglyphics↗
PubMed1985

Receptor-mediated endocytosis of human transferrin and its cell surface receptor.

We have studied the process of transferrin endocytosis in human erythromyeloid cell line K562 using fluorescein (FL) and rhodamine (RD) labeled iron-saturated transferrin (FeTF), and a fluorescein labeled monoclonal antibody to the transferrin receptor (FL-mAB). Because the antireceptor antibody and FeTF bind to different sites on the TF receptor molecule, it is possible to simultaneously and independently follow receptor and ligand. We have measured the relative amounts of transferrin or antireceptor antibody bound in the presence or absence of proteolytic enzymes using a cell sorter. At 4 degrees C almost all of the FL-TF and the FL-mAB is surface bound in a diffuse pattern. Within minutes of elevating the temperature to 37 degrees C surface aggregates form and the FL-TF is internalized. At this time about one sixth of the transferrin is still surface bound and accessible to papain digestion. The remainder localizes in a perinuclear cluster of vesicles. Monoclonal antibody binds to the cell surface transferrin receptor but is not internalized at 4 degrees C or 37 degrees C. When unlabeled diferric transferrin is added, it promotes the uptake of the Fl-mAB. The addition of goat anti-mouse immunoglobulin also promotes FL-mAB uptake. These studies support the concept that a specific trigger is required for transferrin receptor endocytosis.

Animals↗