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Influence of parasite load in memory T and B cell responses and in protective immunity against Plasmodium chabaudi as blood stages

A P F Do Rosário S M Muxel; L R Sardinha; José Maria Alvarez; Maria Regina D'Império Lima; Meeting of the Brazilian Society for Immunology (31. 2006 Búzios)

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

São Paulo 2006

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  • Título:
    Influence of parasite load in memory T and B cell responses and in protective immunity against Plasmodium chabaudi as blood stages
  • Autor: A P F Do Rosário
  • S M Muxel; L R Sardinha; José Maria Alvarez; Maria Regina D'Império Lima; 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 and Objective: The natural acquisition of full protection against malaria, a major cause of death in tropical countries, is thought to be defective because many infections are required to achieve clinical immunity, persistent infection is a common disease feature and protective immunity is easily lost. Thus, this study aims to verify the influence of parasite load in memory T and B cell responses and in protective immunity against P. chabaudi AS. Methods: C57BL/6 mice infected with 106 parasitized eritrocytes (PE) were submitted to patent (uncontrolled) or subpatent infection (controlled with non-curative doses of chloroquine every time 1% parasitemia was reached). Spleen cells were analyzed at 20, 60, 120 and 200 days of infection, according to surface expression of CD4, CD8, CD62L, CD45RB, B220, IgG and to PE-specific CD4+ cell proliferation. Parasitemia and spleen cell phenotype were monitored after challenge with 108 PE. Results: At day 20, the subpatent group presented higher numbers of CD4+ and CD8+ cells than the patent group, but the ratio of effector memory/activated CD4+ cells (CD62LlowCD45RBlow/high) was higher in the patent group (59% compared to 43%). On the next days, the percentages of these cells tended to be similar in both groups. At day 20, 31% and 37% of CD4+ cells proliferated in response to PE in patent and subpatent groups, respectively. However, in both groups, this response was progressively
    reduced, being negative at day 200. Regarding memory B cells, peak values were attained at day 20, when 11% and 9% of CD45R+ cells from patent and subpatent groups expressed sIgG. Even though, the subpatent group showed a higher increase of these cells after challenge. The analysis of parasitemia after challenge revealed that both groups of mice were similarly protected, but the ability to control infection was diminished at day 200. Conclusions: Although the parasite load has a great influence in the acute immune response to P. chabaudi AS, it does not seem to affect the generation and the maintenance of T and B cell memory. This study also shows that the anamnesic response and the protective immunity decline after parasite elimination. Keywords: memory T and B cells, Plasmodium chabaudi.
  • Editor: São Paulo
  • Data de criação/publicação: 2006
  • Formato: res. CI.035.
  • Idioma: Inglês
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  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

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