Role of B7 costimulatory molecules in immune responses and T-helper cell differentiation in response to recombinant HagB from Porphyromonas gingivalis.
Infect Immun
; 72(2): 637-44, 2004 Feb.
Article
de En
| MEDLINE
| ID: mdl-14742503
ABSTRACT
In addition to antigen-specific signals mediated through the T-cell receptor, T cells also require antigen nonspecific costimulation for activation. The B7 family of molecules on antigen-presenting cells, which include B7-1 (CD80) and B7-2 (CD86), play important roles in providing costimulatory signals required for development of antigen-specific immune responses. Hemagglutinin B (HagB) is a nonfimbrial adhesin of the periodontopathic microorganism Porphyromonas gingivalis and is thought to be involved in the attachment of the bacterium to host tissues. However, the immune mechanisms involved in responses to HagB and their roles in pathogenesis have yet to be elucidated. Therefore, the purpose of this study was to determine the role of B7 costimulatory molecules on T-helper-cell differentiation for the induction of immune responses to HagB. Mice deficient in either or both of the costimulatory molecules B7-1 and B7-2 were used to explore their role in immune responses to HagB after subcutaneous immunization. B7-1(-/-) mice had levels of immunoglobulin G (IgG) anti-HagB antibody activity in serum similar to those of wild-type mice, whereas lower serum IgG anti-HagB antibody responses were seen in B7-2(-/-) mice. Moreover, significantly lower numbers of IgG antibody-secreting cells and lower levels of CD4(+)-T-cell proliferation were observed in B7-2(-/-) mice compared to wild-type mice. No serum IgG response to HagB was detected in B7-1/B7-2(-/-) mice. Analysis of the subclass of the serum IgG responses and the cytokines induced in response to HagB revealed that B7-2(-/-) mice had significantly lower IgG1 and higher IgG2a anti-HagB antibody responses compared to wild-type mice. The B7-2(-/-) mice also had significantly reduced levels of interleukin-4 (IL-4) and IL-5 and enhanced level of gamma interferon. Furthermore, assessment of B7-1 and B7-2 expression on B cells and macrophages derived from wild-type BALB/c mice after in vitro stimulation with HagB revealed a predominant upregulation in the expression of the B7-2 costimulatory molecule on B cells and macrophages. Essentially no change was seen in the expression of B7-1. Taken together, these results suggest a critical role for B7, especially B7-2, for the preferential induction of a Th2-like response to HagB.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Protéines bactériennes
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Glycoprotéines membranaires
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Lymphocytes T CD4/
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Antigènes CD
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Antigène CD80
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Porphyromonas gingivalis
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Hémagglutinines
Limites:
Animals
Langue:
En
Journal:
Infect Immun
Année:
2004
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique
Pays de publication:
EEUU
/
ESTADOS UNIDOS
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ESTADOS UNIDOS DA AMERICA
/
EUA
/
UNITED STATES
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UNITED STATES OF AMERICA
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US
/
USA