title: Suppression of circulating IgD+CD27+ memory B cells in infants living in a malaria-endemic region of Kenya.
abstract: BACKGROUND
  Plasmodium falciparum infection leads to alterations in B cell subset distribution. During infancy, development of peripheral B cell subsets is also occurring. However, it is unknown if infants living a malaria endemic region have alterations in B cell subsets that is independent of an age effect.
  
  
  METHODS
  To evaluate the impact of exposure to P. falciparum on B cell development in infants, flow cytometry was used to analyse the distribution and phenotypic characteristic of B cell subsets in infant cohorts prospectively followed at 12, 18 and 24 months from two geographically proximate regions in western Kenya with divergent malaria exposure i.e. Kisumu (malaria-endemic, n = 24) and Nandi (unstable malaria transmission, n = 21).
  
  
  RESULTS
  There was significantly higher frequency and absolute cell numbers of CD19+ B cells in Kisumu relative to Nandi at 12(p = 0.0440), 18(p = 0.0210) and 24 months (p = 0.0493). No differences were observed between the infants from the two sites in frequencies of naïve B cells (IgD+CD27-) or classical memory B cells (IgD-CD27+). However, immature transitional B cells (CD19+CD10+CD34-) were higher in Kisumu relative to Nandi at all three ages. In contrast, the levels of non-class switched memory B cells (CD19+IgD+CD27+) were significantly lower overall in Kisumu relative to Nandi at significantly at 12 (p = 0.0144), 18 (p = 0.0013) and 24 months (p = 0.0129).
  
  
  CONCLUSIONS
  These data suggest that infants living in malaria endemic regions have altered B cell subset distribution. Further studies are needed to understand the functional significance of these changes and long-term impact on ability of these infants to develop antibody responses to P. falciparum and heterologous infections.
authors.affiliation: Maseno University, Maseno, Kenya. Jakogwanjo@gmail.com
authors.forename: Amolo S
authors.initials: AS
authors.lastname: Asito
authors.forename: Erwan
authors.initials: E
authors.lastname: Piriou
authors.forename: Walter G Z O
authors.initials: WG
authors.lastname: Jura
authors.forename: Collins
authors.initials: C
authors.lastname: Ouma
authors.forename: Peter S
authors.initials: PS
authors.lastname: Odada
authors.forename: Sidney
authors.initials: S
authors.lastname: Ogola
authors.forename: Nancy
authors.initials: N
authors.lastname: Fiore
authors.forename: Rosemary
authors.initials: R
authors.lastname: Rochford
mesh_terms: D018941:Antigens, CD19 / Q000276:immunology; D018952:Antigens, CD34 / Q000276:immunology; D016175:B-Lymphocyte Subsets / Q000276:immunology*; D015415:Biomarkers / Q000097:blood; D019353:Endemic Diseases; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007072:Immunoglobulin D / Q000276:immunology*; D007156:Immunologic Memory; D016130:Immunophenotyping; D007223:Infant; D007630:Kenya / Q000453:epidemiology; D007963:Leukocytes, Mononuclear / Q000276:immunology; D018655:Lymphocyte Count; D016778:Malaria, Falciparum / Q000097:blood / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D015260:Neprilysin / Q000276:immunology; D010641:Phenotype; D010963:Plasmodium falciparum / Q000276:immunology / Q000472:pathogenicity; D011446:Prospective Studies; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7 / Q000276:immunology*
chemical_list: D018941:Antigens, CD19; D018952:Antigens, CD34; D015415:Biomarkers; D007072:Immunoglobulin D; D018127:Tumor Necrosis Factor Receptor Superfamily, Member 7; D015260:Neprilysin