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Genetic deficiency of CD28 leads to a more severe pulmonary paracoccidioidomycosis (PCM) at the chronic phase of infection

M Felonato Vera Lúcia Garcia Calich; Meeting of the Brazilian Society for Immunology (31. 2006 Búzios)

Abstracts São Paulo, SP: Brazilian Society for Immunology, 2006

São Paulo 2006

Item não circula. Consulte sua biblioteca.(Acessar)

  • Título:
    Genetic deficiency of CD28 leads to a more severe pulmonary paracoccidioidomycosis (PCM) at the chronic phase of infection
  • Autor: M Felonato
  • Vera Lúcia Garcia Calich; Meeting of the Brazilian Society for Immunology (31. 2006 Búzios)
  • Assuntos: IMUNOLOGIA
  • É parte de: Abstracts São Paulo, SP: Brazilian Society for Immunology, 2006
  • Notas: Disponível em CD-ROM
  • Descrição: Introduction : It has been accepted that two signals are necessary for an adequate activation of the immune system. The first signal is the cognitive interaction between the TCR receptor on T lymphocytes and peptide presented by MHC molecules of APC cells. The balance between accessory molecules on T cells and APC has been considered the second signal. The interaction CD28 molecules of T lymphocytes with APC B7 molecules results in T cell activation, proliferation and subsequent differentiation into effector or memory cells. As the main protective mechanism to PCM is mediated by T cell immunity, the purpose of this work was to investigate the role of the costimulatory signal mediated CD28 molecules in the innate and adaptative phases of immunity induced by P.brasiliensis (Pb) infection. Methods: Wild type (WT) and CD28KO C57BL/6 (KO) mice were i.t. infected with 1x106 yeast cells of Pb 18. Mice were sacrificed 72h, 2 and 10 weeks after infection and the severity of the disease determined by organ CFU counts (means ± standard errors) and analyzed by Student's t test. Antibodies were measured by ELISA. Results: At 72h post infection both mice strains showed similar fungal burdens in the lungs parenchyma (KO 4,01± 0,34 log10 and WT 4,11± 0,23 log10). At the same time point, no differences were observed in fungal loads recovered from bronchoalveolar lavage fluids of KO (3,60 ± 0,31 log10 and WT 3,65 ± 0,09 log10) mice. Again, at
    week 2 after infection no differences were detected between fungal loads of KO (5,32 ± 0,10 log10 and WT 4,96 ± 0,14 log10) mice. However, by week 10 KO mice (5,67 ± 0,19 log10) presented increased pulmonary fungal burdens in comparison with WT mice (4,58 ± 0,30 log10). At this period of infection an impressive difference in antibody production was detected. WT mice produced significantly increased levels of total IgG, IgG1, IgG2a and IgG2b specific isotypes (p<0,001). Conclusions: Our results suggest that the CD28 molecule is not important at acute phase of murine PCM, while at the chronic phase this molecule seems to be essential to the control of humoral immunity and severity of PCM.
  • Editor: São Paulo
  • Data de criação/publicação: 2006
  • Formato: res. ID.191.
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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