Mast Cell Receptor Research Articles

Surface histamine receptors in rat peritoneal mast cells. Separation of receptor-bearing cells via binding to a histamine-protein conjugate, Cell-ect.

The Seragen Cell-ect Total Histamine KitTM was used to separate histamine receptor-bearing rat peritoneal mast cells from cells lacking these receptors. It was found that approximately 75% of the peritoneal mast cell population carried cell surface histamine receptors. The results further suggest that the mast cell histamine receptors present are mainly of an H1-type, as judged by the capacity of a specific H1-antagonist to reduce the histamine receptor-dependent cell adhesion. Moreover, an H1-agonist is less efficient in this respect and an H2-antagonist does not affect the cell adhesion at all. A possible functional role for these receptors, however, remains to be clarified.

Selective phosphorylation of the IgE receptor in antigen-stimulated rat mast cells.

Purified rat serosal mast cells were sensitized with mouse immunoglobulin E (IgE) anti-2,4-dinitrophenyl antibody, partially depleted of phosphate, labeled with [32P]orthophosphate, and stimulated with dinitrophenylated bovine serum albumin or control protein. After 15-120 seconds at 37 degrees C, the cells were extracted with nonionic detergent. IgE receptors were purified by repetitive affinity chromatography and were analyzed by NaDodSO4/polyacrylamide gel electrophoresis and radioautography. Antigenic stimulation of intact rat mast cells produced a rapid and marked increase in the phosphorylation of the surface-exposed alpha component of the IgE receptor. However, phosphorylation of the 33,000 Mr beta component of the IgE receptor was not altered significantly by antigen stimulation. This suggests that the selective increase in phosphorylation of the IgE receptor alpha component may be part of the physiologic mediator secretion process triggered by antigen.

Functional characterization of specific IgE antibodies for tetanus toxoid.

The specific IgE response that appears in subjects immunized with tetanus toxoid does not induce hypersensitivity reactions at subsequent immunizations. The type I immune response, therefore, was studied both in vivo and in vitro, in 11 subjects who had specific IgE antibodies for tetanus toxoid. The results showed that: 1. the specific IgE antibodies are heterogeneous regarding their affinity for the mast cell and basophil receptors; 2. the specific IgG antibodies for tetanus toxoid, at serum concentrations, are not able to interfere with the in vitro specific basophil degranulation; 3. in the PEG precipitate there are aggregates of specific IgE antibodies for tetanus toxoid. In vitro, these molecular aggregates are not able to sensitize the basophil cells.

Possible conformations involved in the binding of neurotensin, xenopsin and bradykinin molecules to mast cell receptors

Possible conformations involved in the binding of neurotensin, xenopsin and bradykinin molecules to mast cell receptors

Characterization of the beta-adrenergic receptor in rat mast cells

Characterization of the beta-adrenergic receptor in rat mast cells

Receptor-secretion coupling in mast cells

The cross-linking of membrane receptors in mast cells and basophil leucocytes initiates a series of biochemical changes, involving methylations in membrane lipids. The result of these events is the increase of membrane permeability to calcium which leads to the secretion of histamine.

Mast cell membrane antigens and Fc receptors in anaphylaxis: II. Functionally distinct receptors for IgG and for IgE on mouse mast cells

The present work was aimed at analyzing the functional relationships between mouse mast cell receptors for IgG and IgE antibodies. It was based on a study of the inhibition of IgG1-and IgE-induced passive mast cell degranulation produced by various immunoglobulin preparations capable of interfering with Fc receptors. Rat myeloma IgE, a high-affinity ligand for IgE receptors, was used to search for a possible participation of IgE receptors in IgG1-dependent degranulation. Mouse myeloma IgG, which inhibited only weakly IgG1-mediated reactions, had no chance to compete successfully with high-affinity IgE antibodies, but aggregated HGG was found to behave as a high-affinity ligand for IgG receptors. This enabled us to search for a possible participation of IgG receptors in IgE-dependent degranulation. The results show that rat myeloma IgE and aggregated HGG specifically inhibited IgE-induced and IgG1-induced reactions, respectively, but failed to inhibit reactions not requiring free Fc receptors. The conclusion was that receptors for IgG and for IgE are functionally independent on mouse mast cells, and are both expressed on the same cells.

Parasite-induced 'nonspecific' IgE does not protect against allergic reactions.

High levels of immunoglobulin E (IgE) are produced in animals, including man, infected with helminth parasites1,2. Such infection results not only in the production of parasite-specific IgE but also, through polyclonal stimulation of IgE-B cells, in the production of a large excess of parasitic nonspecific IgE3. IgE antibodies mediate allergic reactions by binding to receptors on the plasma membrane of mast cells, which are then said to be sensitised; subsequent attachment of antigen to the membrane-bound antibody causes cross-linking of the receptors leading to the release of histamine and other active substances4. Mast cells can be passively sensitised both in vivo and in vitro and passive sensitisation with a specific IgE antibody may be inhibited by prior saturation of IgE receptors with an excess of ‘nonspecific’ IgE5,6. In this way, helminth-infected animals become refractory to passive sensitisation, as do animals bearing IgE myelomas, because of the pre-emption of mast-cell receptors by endogenous IgE7,8. These findings gave rise to two related ideas: first, that it might be possible to ameliorate allergic diseases by passively administering, or by actively stimulating the production of a large amount of ‘irrelevant’ IgE; and second, that a high parasite-induced IgE level might protect against unrelated allergies by means of competition for mast cell receptors6,7,9. However, searches for epidemiological evidence of such a protective effect have had conflicting results10–21. We have examined this question using egg-albumin (E A)-hypersensitive rats infected with Nippostrongylus brasiliensis and now show that ‘nonspecific’ IgE induced by helminth infection, although having the capacity to block passive sensitisation, does not inhibit hypersensitivity reactions mediated by an actively produced IgE antibody.

Cholinergic histamine release: evidence of muscarinic receptors in rat mast cells [proceedings

Cholinergic histamine release: evidence of muscarinic receptors in rat mast cells [proceedings

Mast cell binding of neurotensin. I. Iodination of neurotensin and characterization of the interaction of neurotensin with mast cell receptor sites.

Neurotensin was iodinated at equimolar concentrations of peptide, iodide, and chloramine-T, producing a labeled peptide with a specific activity of 1000 to 2000 Ci/mmol. Rat mast cells specifically and reversibly bound 1.27 pmol of neurotensin/10(6) cells with a reversible affinity, KD, of 154 nM. Optimum specific binding occurred betwen pH 6.8 and 7.2 under hypotonic conditions and dropped sharply as buffer concentration increased beyond 10 mM. The divalent cations Ca2+ and Mg2+ prevented binding with 50% inhibition at 1.5 and 4 mM, respectively. Binding was strongly and equally inhibited by the sodium and potassium salts of chloride, bromide, and iodide, and to a lesser degree by LiCl. Maximum binding of 125I-neurotensin occurred within 10 min at 0 degrees, and within 1.5 to 2 min binding was reduced to half-maximum in the presence of excess unlabeled neurotensin or upon 20-fold dilution in buffer. Both CaCl2 and NaCl were able to dissociate 60% of the total bound neurotensin: half the label bound was removed in 4 to 6 min. EDTA inhibited the binding only at high concentrations and no requirement was found for sulfhydryl groups, ATP, or a glycoprotein in the binding of neurotensin.

Mast cell binding of neurotensin. II. Molecular conformation of neurotensin involved in the stereospecific binding to mast cell receptor sites.

Systematic substitution of the natural L-amino acids in neurotensin by their D isomers reveals that the COOH-terminal portion of this tridecapeptide is required for binding to mast cell receptors: D-amino acid replacements from Pro10 through Leu13 substantially decrease that binding. Either blockage of the COOH-terminal carboxyl group as with N-methylamidation, or formation of a cyclic structure by the inclusion of a disulfide bond, a Cys2,13 substitution, markedly reduces the specific binding to mast cell receptor sites. Modifications in the NH2-terminal portion of neurotensin do not affect the binding to mast cells. However, D-Arg8 and D-Arg9 substitutions increase binding by factors of 5- to 6-fold. The hydroxyl group at position 3 or 11 is not essential for binding since Phe3 or Phe11 is equivalent to Tyr3 or Tyr11. The COOH-terminal penta- and hexapeptides are able to displace approximately 70% 125I-neurotensin relative to the intact peptide. Of 18 other biologically active peptides tested, only xenopsin, a naturally occurring COOH-terminal analog of neurotensin, and bradykinin effectively compete in the binding assay to an extent of 60 and 100%, respectively. Histamine, diphenhydramine, and noradrenaline are ineffective in this regard.

Receptors for C3 on Rat Peritoneal Mast Cells

Purified rat peritoneal mast cells adhere to schistosomula of Schistosoma mansoni which have been pre-incubated in fresh normal rat serum. This cytoadherence reaction is dependent on complement and in particular on components of the alternative pathway. Since antibodies to rat C3 but not IgG block the attachment of the cells to the complement-treated larvae, it appears that C3-specific receptors on the mast cell surface are responsible for the adherence phenomenon. These receptors can also be demonstrated by the rosetting of mast cells with rat complement-treated zymosan particles or fluoresceinated bacteria. The key properties of the receptors are their specificity for homologous (rat) complement, their sensitivity to digestion with trypsin, and their functional dependence on Mg++ ions. Thus, the rat mast cell receptors share many of the characteristics of the C3 receptors previously identified on monocytes, macrophages, and polymorphonuclear leukocytes.

Binding Parameters of the Interaction Between Rat IgE and Rat Mast Cell Receptors

Rat monoclonal IgE was purified by a combination of gel filtration and isoelectric focusing. The binding parameters of the IgE-target cell interaction were studied. The target cells used were normal rat peritoneal mast cells (RMC) and neoplastic rat basophilic leukocytes (RBL). BINDING assays were performed by adding different amounts of IgE to a constant cell number. A Scatchard analysis of the data indicated that both cell types have a similar affinity for rat IgE; the equilibrium constant was in the order of 10-9 M-minus 1. However, RBL have a higher number of receptor sites per cell--approximately 6 times 10-5 versus 3 times 10-5 for normal RMC. Since RMC have more than double the surface area of RBL, the data indicate a much higher receptor density on RBL.

Interaction in Vivo of Homocytotropic Antibodies Belonging to Two Different Rat Immunoglobulin Classes: Effect of IgE on the Passive Cutaneous Anaphylactic Reaction Mediated by IgGa Antibodies

Abstract Rat anti-Nippostrongylus brasiliensis antiserum was considerably more effective than normal rat serum in inhibiting the passive cutaneous anaphylactic (PCA) reaction mediated by an IgGa anti-dinitrophenyl (DNP) antiserum fraction. The inhibitory activity had the chromatographic, gel filtration and heat lability characteristics of rat IgE. The IgGa fraction, isolated from hyperimmune rat anti-DNP antiserum, devoid of IgE anti-DNP activity, yielded stronger 6-hr PCA reactions than did whole antiserum. The inhibitory activity in whole antiserum was attributed to nonspecific IgE, although the existence of other, minor, inhibitors could not be excluded. Rats repeatedly infected with N. brasiliensis larvae failed to undergo PCA reactions at sites prepared with certain IgGa or IgE antibody-containing fractions; it is presumed that in these animals mast cell receptors are occupied by autologous IgE anti-worm antibodies. These experiments provide in vivo confirmation of the interaction of rat IgE and IgGa antibodies at a common receptor on target cells.

Immunoglobulin Receptors on a Mouse Mast Cell Tumor

Abstract Surface receptors for IgG immunoglobulins have been demonstrated on a mouse mast cell tumor growing in tissue culture. Inhibition of rosette formation between mastocytoma cells and IgG-coated SRBC by purified mouse immunoglobulins indicated receptor specificity for all known IgG globulin classes but not for IgM, IgA or light chain immunoglobulins. Pepsin-digested IgG antibody-coated SRBC did not bind to the mast cell. Mast cell receptors appear to react with immunoglobulin-antigen complexes more strongly than with immunoglobulin alone. Receptor activity was unaffected by phospholipase D, neuraminidase or azide and was reduced by phospholipase C, iodoacetamide and fluorescein isothiocyanate. Actinomycin D had no effect for periods up to 9 hr. Treatment of mast cells with trypsin enhanced receptor activity but did not alter specificity. Our initial conclusion is that the mastocytoma IgG-receptor is a stable phospholipid or phospholipoprotein which is protease-resistant.