title: Lymphocyte proliferation and antibody responses to Plasmodium falciparum liver-stage antigen-1 in a highland area of Kenya with seasonal variation in malaria transmission.
abstract: Lymphocyte proliferation and antibody responses to five peptides corresponding to the N- and C-terminal non-repeat and central repeat regions of Plasmodium falciparum liver-stage antigen-1 (LSA-1) were examined in residents of a highland area of Kenya where malaria transmission is episodic and varies with rainfall. The frequency of lymphocyte proliferation responses (stimulation index > 2) by children (persons > or = 6 years old) and adults (persons > or = 18 years old) was similar and did not differ significantly across seasons. In contrast, the proportion of individuals with IgG antibodies to LSA-1 peptides was higher in the rainy than dry season, and the frequency of these responses was greater for adults than children (39.4% versus 18.7% during the period of high transmission; P = 0.009). Antibodies to LSA-1 were primarily of the IgG1 and IgG3 subclasses, and these also varied with season (30.1% and 32.5% of individuals had IgG1 and IgG3 in the rainy season versus none and 10.9% in the dry season). There was no significant difference in the time to re-infection between groups of persons with or without IgG antibody or lymphocyte proliferation responses to LSA-1 peptides. These data indicate that age and transmission intensity independently affect IgG antibody responses to LSA-1 but do not influence lymphocyte proliferation in this highland area where malaria transmission is highly variable.
authors.affiliation: Division of Geographic Medicine, Case Western Reserve University School of Medicine, University Hospitals of Cleveland, Ohio 44106-4983, USA. ccj@po.cwru.edu
authors.forename: Chandy C
authors.initials: CC
authors.lastname: John
authors.forename: John H
authors.initials: JH
authors.lastname: Ouma
authors.forename: Peter O
authors.initials: PO
authors.lastname: Sumba
authors.forename: Michael R
authors.initials: MR
authors.lastname: Hollingdale
authors.forename: James W
authors.initials: JW
authors.lastname: Kazura
authors.forename: Chris L
authors.initials: CL
authors.lastname: King
mesh_terms: D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood*; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000145:classification; D007630:Kenya; D007963:Leukocytes, Mononuclear / Q000276:immunology; D008099:Liver / Q000469:parasitology; D008213:Lymphocyte Activation / Q000276:immunology*; D016778:Malaria, Falciparum / Q000276:immunology / Q000469:parasitology / Q000635:transmission*; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D010963:Plasmodium falciparum / Q000276:immunology*; D012621:Seasons
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007074:Immunoglobulin G; D010455:Peptides; C067302:liver stage-specific antigen, Plasmodium