title: Influence of carriage of hemoglobin AS and the Fc gamma receptor IIa-R131 allele on levels of immunoglobulin G2 antibodies to Plasmodium falciparum merozoite antigens in Gabonese children.
abstract: BACKGROUND
  To extend our previous findings showing an imbalanced distribution of immunoglobulin G2 (IgG2) antibodies to Plasmodium falciparum merozoite surface protein 2 (MSP2) and a higher frequency of infection with multiple P. falciparum strains in Gabonese children with sickle cell trait (hemoglobin AS), human Fc gamma receptor (Fc gamma R) IIa (CD32) polymorphism and the rate of in vitro invasion of red blood cells (RBCs) from subjects with either hemoglobin AA or AS by multiple P. falciparum strains were investigated.
  
  
  METHODS
  Fc gamma RIIa mutation at amino acid position 131 (arginine or histidine) was detected by polymerase chain reaction, and in vitro cultures for parasites were used to assess the invasion rate.
  
  
  RESULTS
  Fc gamma RIIa polymorphism is normally distributed in this population, with no preferential carriage by children with hemoglobin AS. Lower levels of IgG2 subclass antibodies to MSP2 peptides were independently associated with the Fc gamma RIIa-R131 allele and with carriage of hemoglobin AS. Our data suggest that IgG3 antibody responses to MSP2 epitopes could be exacerbated by lower IgG2 levels in children with hemoglobin AS.
  
  
  CONCLUSIONS
  The higher rate of invasion of RBCs in the presence of multiple strains may indicate that several invasion pathways are solicited simultaneously, and the longer persistence of ring forms in RBCs from the subjects with hemoglobin AS might reflect a slower multiplication phase, leading to a longer circulation and enhanced phagocytosis of these nonpathogenic parasite forms. This may contribute to the protection against P. falciparum malaria observed in children with hemoglobin AS.
authors.affiliation: Unite de Recherches Medicales, Hopital Albert Schweitzer, Lambarene, Gabon. ffntoumi@hotmail.com
authors.forename: Francine
authors.initials: F
authors.lastname: Ntoumi
authors.forename: Laurence
authors.initials: L
authors.lastname: Flori
authors.forename: Pembe Issamou
authors.initials: PI
authors.lastname: Mayengue
authors.forename: Davy W
authors.initials: DW
authors.lastname: Matondo Maya
authors.forename: Saadou
authors.initials: S
authors.lastname: Issifou
authors.forename: Philippe
authors.initials: P
authors.lastname: Deloron
authors.forename: Bertrand
authors.initials: B
authors.lastname: Lell
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kremsner
authors.forename: Pascal
authors.initials: P
authors.lastname: Rihet
mesh_terms: D000483:Alleles; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004912:Erythrocytes / Q000469:parasitology*; D005681:Gabon; D005838:Genotype; D006441:Hemoglobin A / Q000235:genetics; D006451:Hemoglobin, Sickle / Q000235:genetics*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D016778:Malaria, Falciparum / Q000235:genetics / Q000469:parasitology; D010963:Plasmodium falciparum / Q000145:classification / Q000276:immunology* / Q000472:pathogenicity; D011110:Polymorphism, Genetic; D015800:Protozoan Proteins / Q000276:immunology*; D017452:Receptors, IgG / Q000235:genetics*
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; C445323:FCGR2A protein, human; D006451:Hemoglobin, Sickle; D007074:Immunoglobulin G; D015800:Protozoan Proteins; D017452:Receptors, IgG; C065974:merozoite surface protein 2, Plasmodium; C028672:hemoglobin AA; C028671:hemoglobin AS; D006441:Hemoglobin A