scholarly journals Mechanism of Fc-mediated interaction of eosinophils with immobilized immune complexes: I. Effects of inhibitors and activators of eosinophil function

1982 ◽  
Vol 56 (1) ◽  
pp. 337-356
Author(s):  
R.C. Oliver ◽  
A.M. Glauert ◽  
K.J. Thorne
Keyword(s):  
Protein A ◽  
Fc Receptors ◽  
Calcium Ionophore ◽  
Apparent Molecular Weight ◽  
Direct Consequence ◽  
Fc Receptor ◽  
Calcium Ionophore A23187 ◽  
Cytochalasin D ◽  
Ionophore A23187 ◽  
Staphylococcal Protein A

A protein of apparent molecular weight 55000, designated protein 3, becomes newly detectable on the eosinophil surface as a specific consequence of interaction with antigen-antibody complexes immobilized in agar layers. The effect of various agents upon this interaction has been determined by monitoring the appearance of this protein by lactoperoxidase-catalysed iodination. Other parameters that have been measured include: the attachment of eosinophils to the agar layers and their subsequent degranulation, as measured by the release of granule peroxidase, and the degree of spreading of the eosinophils, as assessed by electron microscopy. Attachment of eosinophils to antibody-coated layers is inhibited by heat-aggregated immunoglobulin G (IgG), suggesting that this attachment is mediated via eosinophil Fc receptors. In addition, agents, such as the eosinophil chemotactic factor Ala-Gly-Ser-Glu, that enhance the expression of Fc receptors also enhance the appearance of protein 3, while agents, such as hydrocortisone, that inhibit the expression of Fc receptors reduce its appearance. It is concluded that the appearance of protein 3 parallels the expression of Fc receptors. Attempts to block the Fc region of the bound antibody with staphylococcal protein A were not successful. These experiments indicated that the Fc region of bound IgG has different binding sites for protein A and for the Fc receptor. The correlation between the appearance of protein 3 and subsequent degranulation of the eosinophils was confirmed by the use of agents, such as cytochalasin D and levamisole, that enhance both the appearance of protein 3 and degranulation. Conversely, hydrocortisone reduces the appearance of protein 3 and inhibits degranulation. Protein 3 does not appear when eosinophils adhere to agar layers coated with concanavalin A instead of antibody and the eosinophils do not degranulate. Addition of the calcium ionophore A23187, while causing the release of granule peroxidase, does not elicit the appearance of protein 3. These observations provided additional evidence that the appearance of protein 3 is a specific consequence of the interaction of eosinophils with antibody-coated surfaces. The fact that protein 3 appears at the eosinophil surface as a direct consequence of the interaction with antibody suggests that this protein is closely associated with the eosinophil Fc receptor. The enhancement of the appearance of protein 3 in the presence of cytochalasin D indicates that the movement and reorientation of both this protein and the Fc receptor are constrained by association with cytoplasmic microfilaments.

scholarly journals Interactions between human eosinophils and schistosomula of schistosoma mansoni. II. The mechanism of irreversible eosinophil adherence

1979 ◽  
Vol 150 (6) ◽  
pp. 1456-1471 ◽  
Author(s):  
AE Butterworth ◽  
MA Vadas ◽  
DL Wassom ◽  
A Dessein ◽  
M Hogan ◽  
...  
Keyword(s):  
Schistosoma Mansoni ◽  
Concanavalin A ◽  
Protein A ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Con A ◽  
Normal Human ◽  
Culture Supernate ◽  
Eosinophil Major Basic Protein

Previous work (1)(1) has shown that normal human eosinophils show a preferential capacity, in comparison with neutrophils, to bind to antibody- coated schistosomula of Schistosoma mansoni. This effect is attributable to a temperature-dependent function of the eosinophil which renders its binding stable and irreversible by aggregated gamma globulin or Staphylococcus aureus protein A. In contrast, the binding of neutrophils is readily reversible by these agents. It has now been shown that the differences observed between eosinophils and neutrophils is a property of their interaction with living schistosomula. When dead or artificially damaged schistosomula were tested, neutrophils showed a markedly enhanced capacity to adhere, in both the presence and absence of anti-chistosomular serum. Subsequent experiments were designed to test the hypothesis that the strong, stable binding of eosinophils was attributable to degranulation, with release of granule contents which would then serve as ligands to bind the cell to the organism. First, an enhanced adherence both of eosinophils and of neutrophils could be demonstrated in the presence of eosinophil major basic protein (MBP) or of protamine, a high molecular weight cation. Second, the binding of eosinophils induced by concanavalin A (Con A) was found to differ markedly from that induced by antischistosomular serum. Con A-mediated binding of eosinophils was fully reversible by alpha-methyl-mannoside, was not associated with damage to the organism, and did not lead to degranulation of the cell, as estimated by measuring the release of MBP into the culture supernate. However, induction of degranulation of concanavalin A-bound eosinophils, but not of neutrophils, with the calcium ionophore A23187 converted the reaction into one which was no longer reversible by alpha- methylmannoside and in which damage to the organism now did occur. These findings support the hypothesis that the stable binding of eosinophils is associated with degranulation, a process which may contribute to the preferential capacity of this cell to mediate antibody-dependent damage to schistosomula.

scholarly journals Further evidence for the involvement of a phosphoprotein in the respiratory burst oxidase of human neutrophils

1986 ◽  
Vol 239 (3) ◽  
pp. 723-731 ◽  
Author(s):  
P G Heyworth ◽  
A W Segal
Keyword(s):  
Respiratory Burst ◽  
Protein A ◽  
Calcium Ionophore ◽  
Calcium Ionophore A23187 ◽  
Human Neutrophils ◽  
Ionophore A23187 ◽  
Receptor Signal ◽  
Latex Beads ◽  
Respiratory Burst Oxidase ◽  
Kinetics Of

Phosphorylation of a 47 kDa protein in human neutrophils is induced by phorbol 12-myristate 13-acetate (PMA), opsonized latex beads, fMet-Leu-Phe, calcium ionophore A23187 and fluoride. All of these stimuli activate the specialized microbicidal respiratory burst of neutrophils, and in each case the kinetics of activation correspond with the kinetics of phosphorylation of the 47 kDa protein. Trifluoperazine (50 microM) and chlorpromazine (100 microM), inhibitors of calmodulin and protein kinase C, abolish the increase in oxygen consumption and selectively prevent phosphorylation of the 47 kDa protein after PMA stimulation. Treatment of neutrophils with pertussis toxin totally inhibits both superoxide production and phosphorylation of this protein in response to fMet-Leu-Phe, but not in response to PMA, indicating that a GTP-binding protein modulates the fMet-Leu-Phe receptor signal. Phosphorylation of the 47 kDa protein, a phenomenon absent from the neutrophils of subjects with autosomal recessive chronic granulomatous disease, which lack the respiratory burst, appears to be the common trigger for activation of the burst in normal neutrophils.

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

Inhibition of Platelet Aggregation by Ethanol in Vitro Shows Specificity for Aggregating Agent Used and Is Influenced by Platelet Lipid Composition

1982 ◽  
Vol 48 (01) ◽  
pp. 049-053 ◽  
Author(s):  
C G Fenn ◽  
J M Littleton
Keyword(s):  
Platelet Aggregation ◽  
Lipid Composition ◽  
Saturated Fatty Acids ◽  
Calcium Ionophore ◽  
Cholesterol Content ◽  
Membrane Lipid ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Increased Sensitivity

SummaryEthanol at physiologically tolerable concentrations inhibited platelet aggregation in vitro in a relatively specific way, which may be influenced by platelet membrane lipid composition. Aggregation to collagen, calcium ionophore A23187 and thrombin (low doses) were often markedly inhibited by ethanol, adrenaline and ADP responses were little affected, and aggregation to exogenous arachidonic acid was actually potentiated by ethanol. Aggregation to collagen, thrombin and A23187 was inhibited more by ethanol in platelets enriched with saturated fatty acids than in those enriched with unsaturated fats. Platelets enriched with cholesterol showed increased sensitivity to ADP, arachidonate and adrenaline but this increase in cholesterol content did not appear to influence the inhibition by ethanol of platelet responses. The results suggest that ethanol may inhibit aggregation by an effect on membrane fluidity and/or calcium mobilization resulting in decreased activity of a membrane-bound phospholipase.

Effects of glucocorticoids on prostaglandin formation by human amnion

1990 ◽  
Vol 68 (6) ◽  
pp. 671-676 ◽  
Author(s):  
William Gibb ◽  
Jean-Claude Lavoie
Keyword(s):  
Calcium Ionophore ◽  
Inhibitory Effect ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Isolated Cells ◽  
Stimulatory Action ◽  
Human Amnion ◽  
Human Labor ◽  
Epidermal Growth

The human amnion may be an important source of prostaglandins involved in the onset of human labor and therefore it is important to define the factors that regulate their formation in this tissue. In the present study we demonstrate that glucocorticoids inhibit prostaglandin production by freshly isolated amnion cells. The inhibitory action of the glucocorticoids, however, changes to a stimulatory action when the cells are maintained in primary culture for a few days. For both inhibition and stimulation, concentrations of 10−8 M dexamethasone or greater were required to give significant effects, and estradiol and progesterone had no effect on the prostaglandin output of the cells. Epidermal growth factor (EGF), which has previously been found to stimulate prostaglandin output by confluent amnion cells, did not alter prostaglandin output of cells initially placed in culture. Furthermore, the stimulatory action of EGF and dexamethasone appeared additive. The calcium ionophore A23187 stimulated prostaglandin output in freshly isolated cells and accentuated the inhibitory effect of dexamethasone. These studies indicate that prostaglandin formation by human amnion during pregnancy could be regulated by glucocorticoids. These steroids are easily available to the amnion by way of cortisone conversion to Cortisol by the maternal decidua. The results also indicate that amnion is capable of responding to glucocorticoids in both a stimulatory and inhibitory fashion and whether one or both actions are of importance in vivo is a question that is as yet unresolved.Key words: prostaglandins, amnion, fetal membranes, glucocorticoids, labor, pregnancy.

Immunologic mast cell-mediated responses and histamine release are attenuated by heparin

1992 ◽  
Vol 73 (3) ◽  
pp. 1093-1101 ◽  
Author(s):  
J. Lucio ◽  
J. D'Brot ◽  
C. B. Guo ◽  
W. M. Abraham ◽  
L. M. Lichtenstein ◽  
...  
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Histamine Release ◽  
Immunoglobulin E ◽  
Specific Antigen ◽  
Calcium Ionophore ◽  
Intradermal Injection ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Dependent Manner

Heparin has been shown to act as a competitive inhibitor of inositol 1,4,5-triphosphate (InsP3) receptors in various cell types. Because InsP3 is one of the second messengers involved in stimulus-secretion coupling in mast cells, it is possible that heparin may inhibit mast cell-mediated reactions. Therefore, in allergic sheep, we tested this hypothesis in two mast cell-mediated reactions induced by immunologic and nonimmunologic stimuli: immediate cutaneous reaction (ICR) and acute bronchoconstrictor response (ABR). In 12 sheep allergic to Ascaris suum antigen, the surface area of the skin wheal was determined 20 min after intradermal injection (0.05 ml) of increasing concentrations of specific antigen, compound 48/80, and histamine, without and after pretreatment with heparin (100, 300, or 1,000 U/kg i.v.). Antigen, compound 48/80, and histamine produced concentration-dependent increases in ICR. Heparin “partially” inhibited the ICR to antigen and compound 48/80 in a dose-dependent manner without modifying the ICR to histamine. The heparin preservative benzyl alcohol was ineffective. In 11 additional sheep, specific lung resistance was measured before and after inhalation challenges with antigen, compound 48/80, and histamine without and with aerosol heparin pretreatment (1,000 U/kg). Heparin blocked the antigen- and compound 48/80-induced bronchoconstriction without modifying the airway effects of histamine. In isolated human uterine mast cells, heparin inhibited the anti-immunoglobulin E- but not the calcium ionophore- (A23187) induced histamine release. These data suggest that heparin inhibits the ICR and ABR induced by stimuli that produce immunologic and nonimmunologic mast cell degranulation without attenuating the effects of histamine.(ABSTRACT TRUNCATED AT 250 WORDS)

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