| 1. |
- Ryan, M, et al.
(författare)
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Distinct T-cell subtypes induced with whole cell and acellular pertussis vaccines in children.
- 1998
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Ingår i: Immunology. - : Wiley. - 0019-2805 .- 1365-2567. ; 93:1, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Recent clinical trials have demonstrated that new generation acellular pertussis vaccines can confer protection against whooping cough. However, the mechanism of protective immunity against Bordetella pertussis infection induced by vaccination remains to be defined. We have examined cellular immune responses in children immunized with a range of acellular and whole cell pertussis vaccines. Immunization of children with a potent whole-cell vaccine induced B. pertussis-specific T cells that secreted interferon-gamma (IFN-gamma), but not interleukin-5 (IL-5). In contrast, T cells from children immunized with acellular pertussis vaccines secreted IFN-gamma and/or IL-5 following stimulation with B. pertussis antigens in vitro. These observations suggest that protective immunity conferred by whole-cell vaccines, like natural immunity, is mediated by type 1 T cells, whereas the mechanism of immune protection generated with acellular vaccines may be more heterogeneous, involving T cells that secreted type 1 and type 2 cytokines.
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| 2. |
- Bennett, Neil A., et al.
(författare)
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Biochemical and catalytic properties of an endoxylanase purified from the culture filtrate of Thermomyces lanuginosus ATCC 46882
- 1998
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Ingår i: Carbohydrate Research. - 0008-6215 .- 1873-426X. ; 306:3, s. 445-455
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Tidskriftsartikel (refereegranskat)abstract
- An endoxylanase (1,4-beta-D-xylan xylanohydrolase, EC 3.2.1.8) from the culture filtrates of T. lanuginosus ATCC 46882 was purified to homogeneity by DEAE-Sepharose and Bio-Gel P-30 column chromatographies. The purified endoxylanase had a specific activity of 888.8 mumol min-1 mg-1 protein and accounted for approximately 30% of the total protein secreted by this fungus. The molecular mass of native (non-denatured) and denatured endoxylanase were 26.3 and 25.7 kD as, respectively. Endoxylanase had a pI of 3.7 and was optimally active between pH 6.0-6.5 and at 75 degrees C. The enzyme showed > 50% of its original activity between pH 5.5-9.0 and at 85 degrees C. The pH and temperature stability studies revealed that this endoxylanase was almost completely stable between pH 5.0-9.0 and up to 60 degrees C for 5 h and at pH 10.0 up to 55 degrees C for 5 h. Thin-layer chromatography (TLC) analysis showed that endoxylanase released mainly xylose (Xyl) and xylobiose (Xyl2) from beechwood 4-O-methyl-D-glucuronoxylan, O-acetyl-4-O-methyl-D-glucuronoxylan and rhodymenan (a beta-(1-->3)-beta(1-->4)-xylan). Also, the enzyme released an acidic xylo-oligosaccharide from 4-O-methyl-D-glucuronoxylan, and an isomeric xylotetraose and an isomeric xylopentaose from rhodymenan. The enzyme hydrolysed [1-3H]-xylo-oligosaccharides in an endofashion, but the hydrolysis of [1-3H]-xylotriose appeared to proceed via transglycosylation. since the xylobiose was the predominant product. Endoxylanase was not active on pNPX and pNPC at 40 and 100 mM for up to 6 h, but showed some activity toward pNPX at 100 mM after 20-24 h. The results suggested that the endoxylanase from T. lanuginosus belongs to family 11.
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| 3. |
- Hörlein, A. J., et al.
(författare)
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Ligand-independent repression by the thyroid hormone receptor mediated by a nuclear receptor co-repressor
- 1995
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Ingår i: Nature. - : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 377:6548, s. 397-404
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Tidskriftsartikel (refereegranskat)abstract
- Thyroid-hormone and retinoic-acid receptors exert their regulatory functions by acting as both activators and repressors of gene expression. A nuclear receptor co-repressor (N-CoR) of relative molecular mass 270K has been identified which mediates ligand-independent inhibition of gene transcription by these receptors, suggesting that the molecular mechanisms of repression by thyroid-hormone and retinoic-acid receptors are analogous to the co-repressor-dependent transcriptional inhibitory mechanisms of yeast and Drosophila.
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| 4. |
- Ryan, M, et al.
(författare)
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Bordetella pertussis respiratory infection in children is associated with preferential activation of type 1 T helper cells.
- 1997
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Ingår i: Journal of Infectious Diseases. - : Oxford University Press (OUP). - 0022-1899 .- 1537-6613. ; 175:5, s. 1246-50
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Tidskriftsartikel (refereegranskat)abstract
- The mechanism of protective immunity against Bordetella pertussis generated following recovery from whooping cough in childhood has not yet been elucidated. Studies with a murine respiratory infection model have indicated that cellular immunity, mediated by Th1 cells, plays a role in the clearance of a primary infection with B. pertussis and in protection against subsequent challenge. In the present study, the induction of B. pertussis-specific Th cell subsets in children was examined. Peripheral blood mononuclear cells from B. pertussis-infected or convalescent children proliferated and secreted cytokines following antigen stimulation in vitro. In contrast, responses were weak or undetectable in the majority of children who had not been infected or vaccinated. In all cases, responding T cells produced interferon-gamma but low or undetectable interleukin-5. The findings suggest that Th1 cells may play a role in protective immunity generated following infection with B. pertussis in children.
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| 5. |
- Ryan, M, et al.
(författare)
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Bordetella pertussis-specific Th1/Th2 cells generated following respiratory infection or immunization with an acellular vaccine : comparison of the T cell cytokine profiles in infants and mice.
- 1997
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Ingår i: Developments in biological standardization. - 0301-5149. ; 89, s. 297-305
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Tidskriftsartikel (refereegranskat)abstract
- In an investigation of cell-mediated immunity against Bordetella pertussis, we found that B. pertussis infection in infants and in mice was associated with the induction of antigen-specific T cells that secrete IFN-g and IL-2, but not IL-4 or IL-5. This cytokine profile is characteristic of Th1 cells that mediate cellular immune responses against a range of intracellular pathogens. An examination of cytokine production following immunization with a three-component acellular vaccine, comprising inactive PT, FHA and pertactin adsorbed to alum, demonstrated that spleen cells from vaccinated mice produced high levels of IL-5, but no detectable IFN-g and low levels of IL-2. In contrast, peripheral blood mononuclear cells from vaccinated infants produced IL-2, IL-5 and IFN-g. These findings highlight significant differences in the immune responses generated by vaccination and natural infection with B. pertussis and demonstrate that the T-cell response induced with an acellular vaccine, although dominated by type 2 cytokines in mice, is more heterogeneous in infants with a Th0 or mixed Th1/Th2 cytokine profile.
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