Plasmodium falciparum liver-stage antigen-1 peptide-specific interferon-gamma responses are not suppressed during uncomplicated malaria in African children

Eur Cytokine Netw. 2001 Oct-Dec;12(4):647-53.

Abstract

Liver-stage antigen (LSA)-1 is a candidate vaccine molecule for Plasmodium falciparum malaria, but knowledge of the evolution of naturally acquired immune responses to LSA-1 in African children is lacking. We therefore assessed cellular immune responses to two defined T cell epitopes of LSA-1, during and after uncomplicated P. falciparum malaria in a group of Gabonese children. In terms of their prevalence, interferon (IFN)-gamma responses of peripheral blood mononuclear cells (PBMC) to an LSA-1 N-terminal peptide, T1, were significantly higher when measured during the acute phase compared with convalescence. IFN-gamma responses to the LSA-J (hinge region) peptide showed a similar profile, but at a lower prevalence. Depletion experiments confirmed that CD8+ T cells are a major source of peptide-driven IFN-gamma, but both lymphoproliferation and the production of IL-10 in response to either of the peptides was low in all children at all times. PBMC from 25% of the children failed to produce IFN-gamma in response to either peptide at any time-point. The results suggest that lymphocytes producing IFN-gamma in response to at least one T cell epitope of LSA-1 are most frequent in the peripheral circulation during the acute phase of P. falciparum malaria. Thus, in this case, the generalised suppression of cell-mediated responses which characterises acute malaria does not affect liver-stage antigen-specific IFN-gamma production. These findings imply that measurements of the frequency of parasite antigen-specific cellular immune responses in clinically healthy individuals may represent significant underestimations, which has important implications for the design of field-based vaccine antigen-related studies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / immunology*
  • Cell Division
  • Child
  • Child, Preschool
  • Epitopes / immunology*
  • Humans
  • Infant
  • Interferon-gamma / biosynthesis*
  • Malaria Vaccines / immunology
  • Malaria, Falciparum / immunology*
  • Molecular Sequence Data
  • Monocytes / cytology
  • Plasmodium falciparum / growth & development
  • Plasmodium falciparum / immunology*

Substances

  • Antigens, Protozoan
  • Epitopes
  • Malaria Vaccines
  • liver stage-specific antigen, Plasmodium
  • Interferon-gamma