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Biomedical subjects

K Furuichi

Publications and source records attributed to K Furuichi.

At least 73 records · Page 4Linked to original sources
PubMed1986

Comparative evaluation of the effect of pharmacological agents on endocytosis and coendocytosis of IgE by rat basophilic leukaemia cells.

The aggregation of IgE bound to rat basophilic leukaemia (RBL) cells leads to the exocytosis of mediators, the endocytosis of the antigen-aggregated mouse IgE anti-DNP, as well as the coendocytosis of some unaggregated monomeric rat IgE (IR162) and/or unbound receptors. We describe here the relative effect on endocytosis and coendocytosis of various pharmacological agents that block or enhance exocytosis. We have previously shown that, unlike exocytosis, endocytosis by RBL and normal rat mast cells was independent of extracellular calcium. We show here that the presence of calcium chelators or antagonists also had no effect on endocytosis of cross-linked IgE. However, coendocytosis of non-cross-linked IgE was partially inhibited by the elimination of extracellular calcium and the addition of calcium chelators such as EDTA or EGTA-Mg2+. Moreover, the addition of calcium antagonists such as Ni2+ and Co2+ (5 mM) to an incubation mixture containing Ca2+ (1 mM) resulted in the complete inhibition of coendocytosis without affecting endocytosis. Other inhibitors of exocytosis such as sodium azide (10-2M), quercetin (10-4M) and dibutyryl cyclic AMP (10-2 M) blocked coendocytosis completely but had no effect on endocytosis. Sodium azide (10 mM) in combination with 2-deoxyglucose (10 mM) effectively inhibited (90%) endocytosis. Cytochalasin B (10-4 M), which was shown to enhance serotonin release, had no effect on the extent of endocytosis or coendocytosis observed 20 min after the initiation of aggregation. Thus, in RBL cells, endocytosis, coendocytosis and exocytosis exhibit distinguishable sensitivities to some pharmacological drugs.

Animals↗
PubMed1985

The receptor for immunoglobulin E on rat basophilic leukemia cells: effect of ligand binding on receptor expression.

We have evaluated the effect of ligand binding on expression of the receptor for IgE on rat basophilic leukemia (RBL) cells. RBL cells were grown in the presence or absence of 131I-labeled IgE and sometimes were also surface labeled with 125I. We found that cells grown in the presence of IgE continued to accumulate receptors at the surface and thus the apparent amount of cell-associated IgE continued to increase. The results obtained suggest that, in the presence of IgE, the elimination of the receptor from the surface was halted or slowed significantly (approximately equal to 80%) while insertion into the membrane of previously synthesized receptor continued.

Animals↗
PubMed1985

The fate of IgE bound to rat basophilic leukemia cells. IV. Functional association between the receptors for IgE.

Rat basophilic leukemia cells (RBL-2H3) have receptors for immunoglobulin E (IgE) and immunoglobulin G (IgG). These receptors for IgE mediate the endocytosis of chemically or immunochemically cross-linked IgE but not monomeric IgE. However, unoccupied receptors were endocytosed with cross-linked IgE. To further assess the degree and specificity of the observed coendocytosis, we exposed cells carrying monomeric rat IgE and monomeric mouse IgE anti-DNP to a DNP-protein conjugate. We found that up to 30% of the surface-bound monomeric rat IgE redistributed at 0 to 4 degrees C and was then internalized at 37 degrees C with the immunochemically cross-linked mouse IgE. To assess the specificity of the coendocytosis, we exposed cells carrying monomeric rat IgE to immunochemically cross-linked mouse IgG. We found that the binding, patching, and endocytosis of cross-linked mouse IgG had no effect on the monomerically bound rat IgE. The rate of coendocytosis was the same as the rate of endocytosis (t 1/2 3 to 5 min). The extent of coendocytosis depended on the extent of endocytosis but was relatively insensitive to changes in the ratio between mouse and rat IgE over a broad range. These results indicate that some of the receptors for IgE are associated in a specific fashion.

Animals↗
PubMed1984

The behavior of the solubilized receptor for immunoglobulin E in polyethylene glycol-detergent solutions: characterization and potential applications.

We studied the effect of polyethylene glycol (PEG) on the solubility of the receptor for immunoglobulin E (IgE) in non-ionic detergent extracts of rat basophilic leukemia (RBL) cells. We found that the precipitation patterns of free and IgE-bound receptor were identical but differed from that of unbound IgE. Thus, 85 to 95% of the free receptor and the IgE-receptor complexes precipitated at 13% PEG in the presence of 0.5% Nonidet P-40, whereas 95% of the unbound IgE remained soluble. A similar degree of differentiation between the precipitation of receptor-bound and unbound IgE was found when we used extracts and PEG solutions prepared with several non-ionic and/or neutral detergents. The intact IgE-receptor complex with the full complement of subunits (alpha, beta, gamma) precipitated more efficiently than the IgE-alpha-chain-complex. The presence of phospholipids, which were previously shown to be important for preservation of the association between the receptor subunits, enhanced the efficiency of precipitation of the IgE-receptor complex. The presence of PEG also had an effect on the solubility of cellular phospholipids and some of the detergents, although the effect of PEG on either could not be directly related to its effect on the solubility of the IgE-receptor complex. The radioiodinated receptor for IgE, much like other radioiodinated RBL cell membrane proteins, was soluble (greater than or equal to 95%) at approximately 7% PEG but could be specifically and efficiently precipitated from crude cell extracts, in the presence of 7% PEG upon the addition of anti-receptor immunoglobulins alone. Using mouse anti-dinitrophenyl IgE antibody, we found that unlike unbound antigen (DNP-BGG) or the IgE-receptor complex, the detergent-solubilized DNP-BGG-IgE-receptor complex was insoluble at 7% PEG. Consequently, PEG can be employed in assays to quantitate the soluble receptor, and to immunoprecipitate it specifically and directly. Moreover, the use of PEG can facilitate the distinction between unbound antigen and antigen-IgE-receptor complex as well as between the latter and IgE-receptor complex.

Animals↗
PubMed1984

The fate of IgE bound to rat basophilic leukemia cells. III. Relationship between antigen-induced endocytosis and serotonin release.

We have previously shown that, unlike monomeric IgE, chemically derived dimers, trimers, and heavier oligomers of IgE were internalized efficiently. This finding suggested that endocytosis, like mediator release, is triggered by cross-linking of the cell surface receptors for IgE. In the present study, we analyzed the temporal and functional relationships between the two events. We used rat basophilic leukemia cells (RBL-HR+-2H3) and rat peritoneal mast cells, which were allowed to bind monomeric 125I mouse IgE hybridoma anti-dinitrophenyl (HI-DNP-E-26-82), and the polyvalent antigen 131I-dinitrophenylated human serum albumin (DNP15-HSA). We found that at 37 degrees C, 50% of the cell surface-bound immune complexes were internalized rapidly (t1/2 3 to 5 min) by RBL-HR+-2H3 cells with only minimal reduction (1/3) in the extent of internalization when very few of the receptors (approximately 5%) were saturated with IgE. Normal mast cells internalized cell surface-bound immune complexes at a similar rate (t1/2 4 to 5 min). Unlike serotonin release, internalization was independent of extracellular calcium and continued to increase as the ratio of DNP15-HSA to IgE increased 10- to 100-fold over the ratio required for optimal histamine release. In the RBL cells, internalization preceded serotonin release, reaching a peak at about 10 min, while the release (t1/2 13 to 19 min) continued for up to 60 min. Presumably, some of the cross-linked IgE internalized less effectively and continued to trigger serotonin release. The reverse relationship between the rates of internalization and release (t1/2 less than 1 min) was found in normal rat mast cells. We conclude that although cross-linking of two or more receptors triggered both endocytosis and exocytosis, the two events are not necessarily sequential.

Animals↗
PubMed1982

Regulation of allergic reaction by aerobic Corynebacterium equi extract, CEF. III. Inhibition of histamine release from rat peritoneal mast cells.

Effects of a water soluble fraction of Corynebacterium equi (CEF) on the histamine release from rat peritoneal mast cells (RPMC) were investigated. The treatment of RPMC with CEF resulted in a significant inhibition of the histamine release from RPMC which was induced by IgE antibody-antigen interaction as well as nonimmunological histamine liberators. CEF was much more effective in inhibition of IgE-mediated histamine release and compound 48/80 or polymyxin B-induced histamine release when the mast cells were treated with CEF prior to the incubation with the antigen or the liberators. In contrast, CEF was equally effective in inhibition of the histamine release by concanavalin A with phosphatidyl serine when the mast cells were treated with CEF prior to or simultaneously with the liberator. Evidence was also presented that CEF inhibits degranulation of mesenteric mast cells induced by immunological as well as nonimmunological mechanisms.

Animals↗
PubMed1981

Regulation of allergic reaction by aerobic Corynebacterium equi extract, CEF. I. Antigen-nonspecific suppression of reaginic antibody response in mice.

The effect of a water-soluble fraction (CEF) that was prepared from an extract of Corynebacterium equi on primary reaginic antibody formation was studied in Balb/c mice. Mice were immunized with a hapten carrier (DNP-OVA) and received intraperitoneal injections of CEF 7 and 2 days prior to, or 2 and 7 days after the immunization. PCA titers of both antihapten (DNP) and anticarrier (OVA) antibodies of IgE class were reduced significantly by the CEF treatment. Evidence was presented in adoptive transfer experiments that the number of IgE-producing cells in the CEF-treated mice was lower than that of controls. Suppression of IgG1 anti-DNP antibody formation was also achieved by the CEF treatment. Formation of IgG1 anti-OVA antibodies, however, was not suppressed significantly by the treatment. The suppressive activities of CEF were shown to be dose-dependent, but timing of CEF administration did not appear critical.

Aerobiosis↗
PubMed1981

Regulation of allergic reactions by aerobic Corynebacterium equi extract, CEF. II. Inhibition of Heterologous PCA and antigen-induced histamine release in rats.

A water-soluble fraction (CEF) obtained from Corynebacterium equi was administered intradermally or intravenously into Sprague-Dawley rats. Passive cutaneous anaphylaxis (PCA) was elicited in these rats along with the controls by sensitization with mouse anti-DNP serum and challenge with the corresponding antigen. PCA reactions were markedly inhibited by the pretreatments of the rats with CEF. Similar treatments of the animals 2-4h after the sensitization did not inhibit PCA. Inhibitory activity of CEF in the pretreated animals was shown to be dose-dependent. Incubation of rat peritoneal mast cells with CEF effectively blocked the binding of murine IgE antibodies to the cells as evidenced by the failure of the treated cells to bind the antibodies. Furthermore, antigen-induced histamine release from rat mast cells, which were sensitized with murine IgE antibodies, was reduced significantly by CEF treatment of the cells prior to the sensitization. Results of this study indicated that CEF inhibits the PCA in rats, presumably by blocking the binding of heterocytotropic antibodies to Fc receptor of mast cells.

Aerobiosis↗
PubMed1980

Evidence for a naturally occurring anti-spermine antibody in normal rabbit serum.

Normal rabbit serum contains an IgG-like component(s) that binds spermine as well as other polyamines. This molecule(s) has the same physicochemical properties as anti-spermine antibody obtained from rabbits immunized with spermine-thyroglobulin conjugates. However, the polyamines-binding IgG-like molecule(s), unlike anti-spermine antibody, is incapable either of precipitating a spermine-bovine serum albumin complex or of binding to a spermine-Sepharose column. These results suggest the existence of a naturally occurring anti-polyamine antibody that may have defective antibody functions.

Animals↗
PubMed1977

Sequential IgM and IgG2 anti-DNP antibody responses against DNP-E. coli and DNP-lipopolysacchardies in guinea-pigs.

When 2,4-dinitrophenylated cells (DNP-E. coli) and lipopolysaccharides (DNP-LPS) of Escherichia coli were injected i.p. into guinea-pigs, they were capable of inducing sequential production of IgM and IgG2 anti-DNP antibodies, both of which were substantially thymus-independent, but only a trace of IgG1 anti-DNP antibody was produced. On the other hand, thymus-dependent DNP-bovine serum albumin (DNP-BSA) induced concomitantly both the IgG1 and IgG2 antibody responses in the presence of LPS. Therefore, the preferential IgG2 antibody response against DNP-LPS seems to be elicited with DNP-LPS itself and not by a combination of mitogenic stimulation with LPS and haptenic stimulation with other contaminating substances carrying DNP residues. Furthermore, it may not be related to affinity of the antibodies produced since there was no significant difference in the affinity for DNP residue between the IgG2 and IgG1 anti-DNP antibodies produced with DNP-E. coli and DNP-BSA, respectively.

Animals↗
PubMed1975

Preferential production of IgG2 anti-hapten antibody by immunization with hapten-conjugated Escherichia coli.

It is well-known that immunization of guinea pigs with hapten-protein conjugates induces concomitant production of IgG1 and IgG2 anti-hapten antibodies. However, the synthesis of antibody to 2, 4-dinitrophenyl groups (DNP) was found to be restricted to one of the IgG antibodies (IgG2 antibody) when guinea pigs were immunized through repeated intraperitoneal injections of 0.1 mg of 2, 4-dinitrophenylated Escherichia coli (DNP-E coli). This selective induction of IgG2 anti-DNP antibody formation occurred both in the presence and absence of Freund's adjuvants, whereas a trace of IgG1 anti-DNP antibody was produced concomitantly on increasing the immunizing dose of DNP-E. coli (3.0 mg) in Freund's complete adjuvant (FAC).

Animals↗