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Biomedical subjects

A F Lopez

Publications and source records attributed to A F Lopez.

102 records · Page 6Linked to original sources
PubMed1986

Recombinant human granulocyte-macrophage colony-stimulating factor stimulates in vitro mature human neutrophil and eosinophil function, surface receptor expression, and survival.

A purified recombinant human granulocyte-macrophage colony stimulating factor (rH GM-CSF) was a powerful stimulator of mature human eosinophils and neutrophils. The purified rH GM-CSF enhanced the cytotoxic activity of neutrophils and eosinophils against antibody-coated targets, stimulated phagocytosis of serum-opsonized yeast by both cell types in a dose-dependent manner, and stimulated neutrophil-mediated iodination in the presence of zymosan. In addition, rH GM-CSF enhanced N-formylmethionylleucylphenylalanine(FMLP)-stimulated degranulation of Cytochalasin B pretreated neutrophils and FMLP-stimulated superoxide production. In contrast, rH GM-CSF did not promote adherence of granulocytes to endothelial cells or plastic surfaces. rH GM-CSF selectively enhanced the surface expression of granulocyte functional antigens 1 and 2, and the Mo1 antigen. rH GM-CSF induced morphological changes and enhanced the survival of both neutrophils and eosinophils by 6 and 9 h, respectively. These experiments show that granulocyte-macrophage colony stimulating factor can selectively stimulate mature granulocyte function.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1986

Effects of purified bacterially synthesized murine multi-CSF (IL-3) on hematopoiesis in normal adult mice.

Normal adult C57BL, BALB/c, and C3H/HeJ mice were injected intraperitoneally three times daily for up to 6 days with 102,000 U (200 ng) per injection of purified, bacterially synthesized, Multipotential colony-stimulating factor (CSF) (Interleukin-3) (rMulti-CSF) and compared with control mice injected with serum/saline with or without added endotoxin (1 ng/mL). Mice injected with rMulti-CSF exhibited tenfold rises in blood eosinophil and twofold to threefold rises in neutrophil and monocyte levels. The spleens from mice injected with rMulti-CSF showed a 50% increase in weight, elevated levels of maturing granulocytes, eosinophils, nucleated erythroid cells and megakaryocytes, and up to 100-fold rises in mast cells. Progenitor cell frequencies in the spleen were elevated sixfold to 18-fold. No significant changes were observed in the marrow. Sixfold to 15-fold rises were observed in peritoneal cell populations of mice injected with rMulti-CSF with evidence of increased peritoneal macrophage phagocytic activity. Livers of C57BL mice, but not of the other strains, exhibited increased numbers of infiltrating hematopoietic cells whereas rises in mast cell numbers were observed in the mesenteric lymph node, skin, and gut in BALB/c and C3H/HeJ mice. Endotoxin was excluded as being responsible for the observed changes except possibly those involving peritoneal macrophage phagocytic activity. The results indicate that the injection of normal mice with rMulti-CSF significantly stimulates the same types of hematopoietic populations as are stimulated in vitro by Multi-CSF and indicate that this and other CSFs should be useful in stimulating hematopoietic repopulation and functional activity in vivo.

Animals↗
PubMed1986

Biologic properties in vitro of a recombinant human granulocyte-macrophage colony-stimulating factor.

Recombinant human granulocyte-macrophage colony-stimulating factor (rH GM-CSF) was purified to homogeneity from medium conditioned by COS cells transfected with a cloned human GM-CSF cDNA and shown to be an effective proliferative stimulus in human marrow cultures for GM and eosinophil colony formation. The specific activity of purified rH GM-CSF in human marrow cultures was calculated to be at least 4 X 10(7) U/mg protein. Clone transfer experiments showed that this proliferation was due to direct stimulation of responding clonogenic cells. Acting alone, rH GM-CSF did not stimulate erythroid colony formation, but in combination with erythropoietin, increased erythroid and multipotential colony formation in cultures of peripheral blood cells. rH GM-CSF had no proliferative effects on adult or fetal murine hematopoietic cells, did not induce differentiation in murine myelomonocytic WEHI-3B cells, and was unable to stimulate the survival or proliferation of murine hematopoietic cell lines dependent on murine multi-CSF (IL 3). rH GM-CSF stimulated antibody-dependent cytolysis of tumor cells by both mature human neutrophils and eosinophils and increased eosinophil autofluorescence and phagocytosis by neutrophils. From a comparison of these effects with those of semipurified preparations of human CSF alpha and -beta, it was concluded that rH GM-CSF exhibited all the biologic activities previously noted for CSF alpha.

Animals↗
PubMed1986

Purified colony-stimulating factors enhance the survival of human neutrophils and eosinophils in vitro: a rapid and sensitive microassay for colony-stimulating factors.

The survival of purified human blood neutrophils and eosinophils was monitored using microwell cultures. Survival was enhanced in cultures containing human or murine colony-stimulating factors (CSFs). The survival of both cell types was enhanced by purified recombinant human granulocyte-macrophage CSF and partially purified preparations of the native molecule, CSF alpha. Neutrophil but not eosinophil survival was enhanced by murine granulocyte-CSF and its human analogue CSF beta. Eosinophil but not neutrophil survival was enhanced by murine eosinophil differentiation factor (eosinophil CSF). The mature cell survival provided an assay system for CSF that was 10(2) to 10(3) more sensitive than the standard assay of stimulation of colony formation in agar cultures and could be completed within 48 hours. These results demonstrated that CSF induced and enhanced survival of mature human neutrophils and eosinophils in vitro. Furthermore, the lineage specificity of purified murine CSFs was retained in their action on human cells.

Animals↗
PubMed1985

Suppression of early immunity to Nematospiroides dubius in mice by selective depletion of neutrophils with monoclonal antibody.

The role of neutrophils and eosinophils in the acquired resistance of mice to infection with the helminth Nematospiroides dubius has been investigated in vivo by testing infected mice for their resistance to a challenge dose of larvae following treatment with monoclonal rat antibodies (MAbs) specific for mouse granulocytes. Treatment of normal and infected mice with NIMP-R10 MAb reduced the number of neutrophils in the peripheral blood and peritoneal cavity during the ensuing 2-5 days without affecting macrophage or eosinophil levels. The effect of this MAb on immunity depended on the immune status of the mice tested. The partial resistance of mice receiving a primary 'immunising' infection, followed by passive transfer of immune serum and challenge at 4 days, was completely suppressed by NIMP-R10 MAb. The acquired resistance of mice challenged 10 days after being given a single 'immunising' infection was halved by NIMP-R10 treatment, while that of 'twice-immunised' mice (infected on days 0 and 14, challenged on day 24) was unaffected. Treatment of twice-infected mice with the eosinophil-specific MAb NIMP-R6 reduced the number of eosinophils in the blood and peritoneal cavity by 40-60%, but caused no significant loss of immunity. The data indicate that after infection of mice with N. dubius, neutrophils play a predominant role in early resistance to reinfection, but they become progressively less essential as activated macrophages and (following a second infection) eosinophils become prevalent. The lack of effect of NIMP-R6 MAb treatment on the immunity of twice-infected mice may have been due to an insufficient reduction in eosinophil numbers; however, it seems likely that the neutrophils and macrophages present in these mice would have provided adequate protection even in the absence of eosinophils.

Animals↗
PubMed1985

The clonal proliferation in vitro of enriched populations of human promyelocytes and myelocytes.

The proliferative capacity of normal human promyelocytes and myelocytes was demonstrated and characterized on the basis of clonal proliferation in agar. An enriched population of normal human promyelocytes and myelocytes was obtained from bone marrow using the monoclonal antibody WEM G11 and the fluorescence-activated cell sorter (FACS). In cultures stimulated by placental-conditioned medium, these cells generated peak total clone numbers between days 3 and 5 of culture. Clones disappeared rapidly thereafter. These clones were mainly of subcolony size at day 7, although some colonies were generated by this population. The clones were primarily neutrophilic in type. These cells had a plating efficiency of up to 50%, and clonal proliferation was dependent on stimulation by colony-stimulating factor (CSF).

Antibodies, Monoclonal↗
PubMed1985

Fractionated populations of normal human marrow cells respond to both human colony-stimulating factors with granulocyte-macrophage activity.

Populations of normal human colony-forming cells (blast cells) and cluster-forming cells (promyelocytes-myelocytes) were obtained from bone marrow by using the monoclonal antibody WEM G11 and the fluorescence-activated cell sorter (FACS). Both populations were shown to be responsive to both human colony-stimulating factors (CSFs) with granulocyte-macrophage activity (CSF alpha and CSF beta), with the cluster-forming cell population being more responsive to CSF beta than the colony-forming cell population. The clonal proliferation of promyelocytes-myelocytes was transient, and the clones generated were of subcolony size (less than 40 cells) regardless of the CSF used. Clone transfer experiments demonstrated that progeny of promyelocytes-myelocytes initiated using one stimulus (CSF alpha or CSF beta) were also responsive to the other stimulus.

Animals↗
PubMed1984

Differentiation antigens on mouse eosinophils and neutrophils identified by monoclonal antibodies.

A panel of hybridomas secreting monoclonal antibodies (mAb) reacting with antigens on mouse eosinophils and neutrophils has been selected. It is shown that four mAb bind preferentially to eosinophils, recognizing antigens expressed between 5 and 25 times more densely on these cells than on neutrophils. One mAb reacts preferentially with neutrophils, binding an antigen about 12 times more common on these cells than on eosinophils. Four mAb are shown to react with both eosinophils and neutrophils, and also macrophages. These mAb confirm the presence of different differentiation antigens on both eosinophils and neutrophils, and show that the myeloid series express antigens not expressed on lymphocytes.

Animals↗
PubMed1984

Mononuclear cell-mediated enhancement of granulocyte function in man.

Human monocyte-enriched mononuclear cells (MNC) (greater than 95% monocytes) powerfully stimulated the antibody-dependent killing of tumor cells by purified human neutrophils (NE) or eosinophils (EO). The enhancement was observed when the mononuclear cell to granulocyte ratio was as low as 1:100. Media conditioned by MNC also stimulated antibody-dependent killing by NE and EO as well as the uptake and killing of Candida albicans by NE. There was a heterogeneity amongst individuals in the capacity of their MNC to elaborate this factor, and approximately 15% of individuals did not produce detectable factor. Different factors in the MNC supernatant were involved in NE and EO activation. The EO-activating factor (AF) had a m.w. of approximately 27,000 and migrated as a single band on phenyl-Sepharose chromatography. The NE-AF had a m.w. of 22,000 and migrated as two distinct bands on phenyl-Sepharose chromatography. EO-colony-stimulating factor (CSF) co-purified with EO-AF, and granulocyte-macrophage-CSF co-purified with both bands of NE-AF. It is concluded that MNC elaborate CSF-like molecules that powerfully stimulate human granulocyte function.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1983

Activation of granulocyte cytotoxic function by purified mouse colony-stimulating factors.

Highly purified mouse colony-stimulating factors (CSF) were tested for their effect on neutrophil cytotoxic function in a homologous antibody-dependent cell-mediated cytotoxicity (ADCC) assay in which TNP-coupled mouse thymoma cells coated with mouse anti-TNP antibodies were used as targets, and purified normal mouse bone marrow neutrophils or induced peritoneal neutrophils were used as effector cells. Biochemically pure granulocyte-macrophage (GM)- and granulocyte (G)-CSF enhanced the cytotoxic activity of neutrophils obtained from both sources, allowing them to kill target cells at low antibody concentrations. Furthermore, GM- and G-CSF showed an additive effect, suggesting either the presence of separate receptors for GM- and G-CSF or of separate subsets of neutrophils. Induced peritoneal neutrophils showed a higher level of basal cytotoxic activity than did bone marrow neutrophils, suggesting neutrophil activation in vivo, but both reached similar levels of cytotoxicity upon maximal stimulation with CSF. In addition, CSF was found to be cross-reactive between mouse and human species in their enhancement of neutrophil cytotoxicity. By testing purified mouse CSF on human neutrophils, it could be shown that G-CSF and GM-CSF are functionally distinct molecules, because only G-CSF enhanced ADCC by human neutrophils. These experiments show that the purified factors that control the production of neutrophils by progenitor cells in vitro also activate differentiated neutrophils to carry out their cytotoxic activity in a more effective manner.

Animals↗
PubMed1978

Antibody dependent cell-mediated cytotoxicity of Trypanosoma cruzi: the release of tritium-labelled RNA, DNA and protein.

The cytotoxicity of normal rat spleen cells to antibody-coated Trypanosoma cruzi epimastigotes has been studied by assaying the release of [3H]-labelled macromolecules from the parasites. The release of thymidine (DNA) is slower than the release of uridine (RNA), suggesting that the nucleus is broken down more slowly than the cytoplasmic membrane. Less than 50% of the leucine (protein) is released when the parasites are lysed, whereas uridine (RNA) is almost totally released. In practical terms these results show that the release of incorporated radioisotope-labelled uridine can be used as a sensitive assay for cytotoxicity of T. cruzi. Cytotoxicity by normal rat spleen cells is antibody dependent and proportional to the logarithm of effector cell number. The lag phase and the rate of RNA release is not altered by centrifuging the parasites and effector cells to enhance contacts between them.

Animals↗