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Biomedical subjects

M Hirashima

Publications and source records attributed to M Hirashima.

At least 91 records · Page 5Linked to original sources
PubMed1983

Modulation of the biologic activities of IgE-binding factors. I. Identification of glycosylation-inhibiting factor as a fragment of lipomodulin.

Splenic T lymphocytes of rats treated with complete Freund's adjuvant (CFA) spontaneously release a lymphokine that inhibits the glycosylation of IgE-binding factors during their biosynthesis and provides the factors with biologic activity: selective suppression of the IgE response. The lymphokine, which is called glycosylation-inhibiting factor, also prevents IgE-induced increases in Fc epsilon R+ cells. The glycosylation inhibiting factor is formed by stimulation of BCG-primed spleen cells with PPD and participates in the selective formation of IgE-suppressive factors. The lymphokine is derived from OX 8+ T cells in both the CFA and BCG systems. The glycosylation-inhibiting factor is a 16,000-dalton peptide, as estimated by gel filtration, and specifically binds to monoclonal antibody against lipomodulin, a phospholipase inhibitory protein. Furthermore, "lipomodulin" was detected by radioimmunoassay in the 16,000-dalton fraction that contained glycosylation inhibiting factor. The fraction did not inhibit phospholipase A2 but after alkaline phosphatase treatment, the fraction did inhibit phospholipase A2. Furthermore, purified lipomodulin obtained from glucocorticoid-treated rabbit neutrophils had the same biologic activities as glycosylation inhibiting factors; i.e., it inhibited both protein glycosylation of IgE-binding factors and IgE-induced expression of Fc epsilon R. The results collectively indicate that glycosylation-inhibiting factor is a fragment of phosphorylated lipomodulin.

Animals↗
PubMed1983

The mediation of tissue eosinophilia in hypersensitivity reactions. IV. Production of delayed eosinophil chemotactic factor-a by peritoneal exudate cells from sensitized guinea-pigs in vitro.

An eosinophil chemotactic factor (ECF) was produced in the cell-free culture supernatants (CFS) of peritoneal exudate cells (PEC) from guinea-pigs immunized with dinitrophenyl derivatives of ascaris extract (DNP-As), when stimulated by the antigen in vitro without activation by immune complexes. A 2 or 6 hr pulse of the antigen was sufficient for ECF production, whereas long time incubation (48 hr) was required for the production of a sufficient amount of the factor. Treatment of PEC by cycloheximide resulted in the reduction of ECF production, suggesting that protein synthesis is essential. Its generation appeared carrier-specific and the source of the factor is presumed to be lymphocytes, probably T lymphocyte. The factor with a molecular weight of 70,000 shared a common antigenicity with delayed eosinophil chemotactic factor-a (delayed ECF-a), which was isolated from the skin lesions showing delayed tissue eosinophilia in vivo.

Animals↗
PubMed1983

The mediation of tissue eosinophilia in hypersensitivity reactions. V. Comparative study of tissue eosinophilia in the skin lesions of local and systemic passive cutaneous anaphylactic reactions.

Tissue eosinophilia in active cutaneous anaphylaxis reactions is biphasic: the early phase (6 hr) is induced by a low molecular (mol. wt. 300) factor (early ECF), and the delayed phase (24 hr) is mediated by synergy of two different factors (delayed ECF-a and -b). In this study, we report the mediation of tissue eosinophilia in passive cutaneous anaphylactic (PCA) reaction sites. Tissue eosinophilia in systemic PCA showed two phases with peaks at 6 hr and 24 hr, while that in local PCA was monophasic and peaked at 12 hr. A dialysable eosinophil chemotactic factor was isolated from the early stage (0-6 hr) of local PCA skin sites, and another chemotactic factor (mol. wt. 15,000), sharing a common antigenicity with guinea-pig serum C5, from 12-hr-old local PCA skin sites. On the other hand, a different chemotactic factor with a mol. wt. of about 70,000, sharing a common antigenicity with delayed ECF-b isolated from active cutaneous anaphylactic skin lesions, was isolated from 24-hr-old systemic PCA skin lesions. Although the dialysable factor was also isolated from systemic PCA skin sites, the factor from systemic PCA delayed skin sites may not contribute to delayed tissue eosinophilia, since the activity paralleled the intensity of basophil accumulation but not to that of eosinophils. It is thus suggested that tissue eosinophilia in systemic and local PCA reactions is mediated by different chemotactic factors.

Animals↗
PubMed1981

Regulation of IgE response by IgE binding factors.

T lymphocytes from rats infected with Nippostrongylus brasiliensis (Nb) release a soluble factor with affinity for IgE that selectively potentiates the IgE response to an unrelated antigen. The factor is derived from Fc omega receptors on T cells, binds to surface IgE on precursors of IgE-forming cells, and enhances their differentiation. The factor had a molecular weight between 10,000 to 20,000 and an affinity for lentil lectin. T cells from Nb-infected rats formed another IgE-binding factor upon incubation with rat IgE. The factor has the ability to suppress rather than enhance the IgE response. The IgE-specific suppressive factor is comparable to IgE-potentiating factor with respect to molecular weight and affinity for IgE but it fails to bind to lentil lectin. The IgE-specific suppressive factor is formed by lymphocytes complete Freund's adjuvant-treated rats. The results strongly suggest that IgE-binding factors are involved in the regulation of IgE response.

Animals↗
PubMed1981

Regulatory role of IgE-binding factors from rat T lymphocytes. V. formation of IgE-potentiating factor by T lymphocytes from rats treated with Bordetella pertussis vaccine.

An i.p. injection of Bordetella pertussis vaccine (BP) into rats induced the formation of soluble factors that had affinity for IgE (IgE-binding factors). The factor was detected in the serum of BP-treated animals 5 to 7 days after the treatment. Their circulating lymphocytes as well as spleen cells spontaneously released IgE-binding factors in the serum of BP-treated rats and those released from their circulating lymphocytes had affinity for lentil lectin, and the ability to selectively potentiate an in vitro IgE response of DNP-OA primed cells to homologous antigen. The molecular size of IgE-potentiating factor was between 10,000 and 20,000, and was comparable to that formed by lymphocytes of rats infected with Nippostrongylus brasiliensis. Evidence was obtained that IgE-potentiating factor was derived from Fc epsilon R(+) T cells, with a T cell marker identified by monoclonal antibody W 3/25. Their production of IgE-potentiating factor may be the basis of the adjuvant effect of BP on the IgE response.

Animals↗
PubMed1981

Lymphocytes bearing Fc receptors for IgE. V. Effect of tunicamycin on the formation of IgE-potentiating factor and IgE-suppressive factor by con A-activated lymphocytes.

Attempts were made to induce the formation of soluble factors having affinity for IgE (IgE-binding factors) by activated T cells. Normal rat mesenteric lymph node (MLN) cells were cultured in 1 microgram/ml Con A for 48 hr or in 10 microgram/ml Con A for 72 hr, and Con A-activated lymphocytes were incubated with rat IgE. It was found that IgE induced an increase in the proportion of Fc epsilon R(+) cells in the Con A-activated cells and formation of IgE-binding factors. However, the nature of IgE-binding factors formed by the cells were different depending on the concentration of Con A for activation. Thus, IgE-binding factors formed by 10 microgram/ml Con A-activated cells had a high affinity for lentil lectin and enhanced the IgE-forming cell response of DNP-OA primed cells. In contrast, the majority of IgE-binding factors formed by 1 microgram/ml Con A-activated cells failed to bind to lentil lectin and suppressed the IgE response. Induction of Fc epsilon R by IgE on Con A-activated cells was prevented by tunicamycin, which inhibits protein glycosylation. This antibiotic did not prevent the IgE-induced formation of IgE-binding factors but changed the nature of the factors formed by 10 microgram/ml Con A-activated cells. The majority of IgE-binding factors formed in the presence of tunicamycin lacked affinity for lentil lectin and Con A, and suppressed, rather than enhanced, the IgE response. The nature and amount of IgE-binding factors formed by 1 microgram/ml Con A-activated cells was not affected by tunicamycin. The results suggest that glycosylation of IgE-binding factors during their biosynthesis is an important step in determining their biologic function.

Animals↗
PubMed1981

Lymphocytes bearing Fc receptors for IgE. VI. Suppressive effect of glucocorticoids on the expression of Fc epsilon receptors and glycosylation of IgE-binding factors.

Incubation of rat lymphocytes with homologous IgE induced an increase in Fc epsilon R(+) lymphocytes and the formation of IgE-binding factors. Pretreatment of rat lymphocytes with 1 to 5 microM dexamethasone, however, prevented the IgE-induced expression of Fc epsilon R on both B and T lymphocytes. Upon incubation with IgE, T cells activated with 10 micrograms/ml Con A produced IgE-potentiating factors that had affinity for lentil lectin and selectively enhanced the IgE response. Pretreatment of the Con A-activated T cells with dexamethasone, before incubation with IgE, changed the nature of IgE-binding factors formed by the cells. The majority of IgE-binding factors formed by the dexamethasone-treated, Con A-activated cells failed to bind lentil lectin Sepharose and selectively suppressed the IgE response. An injection of 0.2 mg dexamethasone into rats infected with Nippostrongylus brasiliensis markedly diminished the proportion of Fc epsilon R(+) lymphocytes in their mesenteric lymph nodes. The lymph node cells from the infected animals spontaneously released IgE-potentiating factors in vitro. However, the majority of IgE-binding factors formed by the mesenteric lymph node cells from the dexamethasone-treated, Nb-infected animals lacked affinity for lentil lectin and selectively suppressed the IgE response. The results indicate that glucocorticoid treatment prevented the glycosylation of IgE-binding factors and thereby changed the biologic activities of the factors.

Animals↗
PubMed1980

Regulatory role of IgE-binding factors from rat T lymphocytes. I. Mechanism of enhancement of IgE response by IgE-potentiating factor.

T lymphocytes in the mesenteric lymph nodes of rats infected with Nippostrongylus brasiliensis spontaneously released a soluble factor that selectively potentiated the IgE-forming cell response of antigen-primed cells to homologous antigen. The factor could enhance the IgE response of DNP-OA-primed cells to DNP-HSA and T cell-replacing factor. In contrast, the treatment of OA-primed T cells with the factor failed to enhance either the IgE or IgG response of the mixture of DNP-KLH primed cells and OA-primed T cells to DNP-OA. The results collectively suggested that the target cells of the IgE-potentiating factor are B cells. Indeed, IgE potentiating factor was absorbed by B cells rather than T cells or thymocytes. Evidence was obtained that IgE-potentiating factor could be absorbed by IgE-bearing B cells or IgE-coupled Sepharose, indicating that the factor had affinity for IgE. It appeared that the potentiating factor bound to IgE-bearing B cells and selectively enhanced the differentiation of IgE-B cells to IgE-forming cells. It was also found that the major source of the factor was Fc epsilon R-bearing T cells.

Absorption↗
PubMed1980

Regulatory role of IgE-binding factors from rat T lymphocytes. II. Glycoprotein nature and source of IgE-potentiating factor.

Previous experiments have shown that Fc epsilon receptor-bearing (Fc epsilon R(+)) T lymphocytes in mesenteric lymph nodes (MLN) of rats infected with Nippostrongylus brasiliensis (Nb) release a soluble factor that selectively potentiates the IgE response. The IgE-potentiating factor has affinity for IgE, and can be detected by the ability to inhibit rosette formation of Fc epsilon R(+) cells with IgE-coated erythrocytes. The factor was bound to IgE-coated Sepharose and was eluted from the beads at acid pH. It was also found that the IgE-potentiating factor binds to lentil lectin-Sepharose, indicating that the factor is a glycoprotein. The affinity of the factor for IgE was lost after treatment with trypsin but was maintained after treatment with neuraminidase. However, the ability of the factor to potentiate the IgE response was lost after neuraminidase treatment. The results suggested that the factor's binding site for IgE is associated with a protein (peptide) moiety but that its carbohydrate moiety is essential for its biologic activity. When MLN cells were incubated at 37 degrees C, a substantial amount of the IgE-potentiating factor was released into culture medium within 4 hr even in the presence of cycloheximide. Pretreatment of the cells with trypsin, which removed Fc epsilon R, markedly diminished the release of IgE-potentiating factor, suggesting that the factor is derived from Fc epsilon R on the cell surface.

Animals↗
PubMed1980

Regulatory role of IgE-binding factors from rat T lymphocytes. III. IgE-specific suppressive factor with IgE-binding activity.

Incubation with rat IgE of rat mesenteric lymph node cells obtained 8 days after infection with Nippostrongylus brasiliensis (Nb) resulted in the formation of soluble factors with affinity for IgE, i.e., IgE-binding factors(s). The factors were derived from T lymphocytes and were able to suppress an in vitro IgE response without affecting the IgG response. The minimum concentration of rat IgE for the induction of factor formation was 0.3 to 1.0 microgram/ml. Gel filtration of culture filtrates of the IgE-containing culture identified 2 components with IgE-binding activity; one component had a m.w. of between 10,000 and 20,000, and another component had a m.w. of between 25,000 and 50,000. Both factors could be purified by binding to IgE-Sepharose followed by elution at acid pH. Among the two IgE-binding factors, the lower m.w. component had the ability to suppress selectively the IgE response. In contrast to IgE-potentiating factor, which also had affinity for IgE, the IgE-suppressive factor failed to bind to lentil lectin Sepharose. Formation of IgE-specific suppressive factor was not limited to the lymphocytes obtained 8 days after Nb-infection. Incubation with IgE of lymphocytes obtained 4 wk after infection resulted in the formation of both IgE-specific suppressive factor and IgE-potentiating factor, and the activity of the suppressive factor was greater than that of the potentiating factor.

Animals↗