Acquired immune responses to Plasmodium falciparum merozoite surface protein-1 in the human fetus

J Immunol. 2002 Jan 1;168(1):356-64. doi: 10.4049/jimmunol.168.1.356.


Infants born in areas of stable malaria transmission are relatively protected against severe morbidity and high density Plasmodium falciparum blood-stage infection. This protection may involve prenatal sensitization and immunologic reactivity to malaria surface ligands that participate in invasion of red cells. We examined cord blood T and B cell immunity to P. falciparum merozoite surface protein-1 (MSP-1) in infants born in an area of stable malaria transmission in Kenya. T cell cytokine responses to the C-terminal 19-kDa fragment of MSP-1 (MSP-1(19)) were detected in 24 of 92 (26%) newborns (4-192 IFN-gamma and 3-88 IL-4-secreting cells per 10(6)/cord blood lymphocytes). Peptide epitopes in the N-terminal block 3 region of MSP-1 also drove IFN-gamma and/or IL-13 production. There was no evidence of prenatal T cell sensitization to liver-stage Ag-1. A total of 5 of 86 (6%) newborns had cord blood anti-MSP-1(19) IgM Abs, an Ig isotype that does not cross the placenta and is therefore of fetal origin. The frequency of neonatal B cell sensitization was higher than that indicated by serology alone, as 5 of 27 (18%) cord blood samples contained B cells that produced IgG when stimulated with MSP-1(19) in vitro. Neonatal B cell IgG responses were restricted to the Q-KNG allele of MSP-1(19), the major variant in this endemic area, whereas T cells responded to all four MSP-1(19) alleles evaluated. In utero sensitization to MSP-1 correlated with the presence of malaria parasites in cord blood (chi(2) = 20, p < 0.0001). These data indicate that prenatal sensitization to blood-stage Ags occurs in infants born in malaria endemic areas.

Publication types

  • Comparative Study
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Antibodies, Protozoan / biosynthesis
  • Antigens, Protozoan / immunology
  • Cells, Cultured
  • Cytokines / biosynthesis
  • Female
  • Fetal Blood / immunology
  • Fetus / immunology*
  • Humans
  • Immunity, Maternally-Acquired*
  • Immunoglobulin G / biosynthesis
  • Malaria, Falciparum / immunology*
  • Merozoite Surface Protein 1 / genetics
  • Merozoite Surface Protein 1 / immunology*
  • Mutation
  • Peptides / immunology
  • Plasmodium falciparum / immunology*
  • Pregnancy
  • T-Lymphocytes / immunology


  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Cytokines
  • Immunoglobulin G
  • Merozoite Surface Protein 1
  • Peptides
  • liver stage-specific antigen, Plasmodium