title: B cell analysis of ethnic groups in Mali with differential susceptibility to malaria.
abstract: BACKGROUND
  Several studies indicate that people of the Fulani ethnic group are less susceptible to malaria compared to those of other ethnic groups living sympatrically in Africa, including the Dogon ethnic group. Although the mechanisms of this protection remain unclear, the Fulani are known to have higher levels of Plasmodium falciparum-specific antibodies of all Ig classes as compared to the Dogon. However, the proportions of B cell subsets in the Fulani and Dogon that may account for differences in the levels of Ig have not been characterized.
  
  
  METHODS
  In this cross-sectional study, venous blood was collected from asymptomatic Fulani (n = 25) and Dogon (n = 25) adults in Mali during the malaria season, and from P. falciparum-naïve adults in the U.S. (n = 8). At the time of the blood collection, P. falciparum infection was detected by blood-smear in 16% of the Fulani and 36% of the Dogon volunteers. Thawed lymphocytes were analysed by flow cytometry to quantify B cell subsets, including immature and naïve B cells; plasma cells; and classical, activated, and atypical memory B cells (MBCs).
  
  
  RESULTS
  The overall distribution of B cell subsets was similar between Fulani and Dogon adults, although the percentage of activated MBCs was higher in the Fulani group (Fulani: 11.07% [95% CI: 9.317 - 12.82]; Dogon: 8.31% [95% CI: 6.378 - 10.23]; P = 0.016). The percentage of atypical MBCs was similar between Fulani and Dogon adults (Fulani: 28.3% [95% CI: 22.73 - 34.88]; Dogon: 29.3% [95% CI: 25.06 - 33.55], but higher than U.S. adults (U.S.: 3.0% [95% CI: -0.21 - 6.164]; P < 0.001). Plasmodium falciparum infection was associated with a higher percentage of plasma cells among Fulani (Fulani infected: 3.3% [95% CI: 1.788 - 4.744]; Fulani uninfected: 1.71% [95% CI: 1.33 - 2.08]; P = 0.011), but not Dogon adults.
  
  
  CONCLUSIONS
  These data show that the malaria-resistant Fulani have a higher percentage of activated MBCs compared to the Dogon, and that P. falciparum infection is associated with a higher percentage of plasma cells in the Fulani compared to the Dogon, findings that may account for the higher levels of P. falciparum antibodies in the Fulani.
authors.affiliation: Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA.
authors.forename: Silvia
authors.initials: S
authors.lastname: Portugal
authors.forename: Didier
authors.initials: D
authors.lastname: Doumtabe
authors.forename: Boubacar
authors.initials: B
authors.lastname: Traore
authors.forename: Louis H
authors.initials: LH
authors.lastname: Miller
authors.forename: Marita
authors.initials: M
authors.lastname: Troye-Blomberg
authors.forename: Ogobara K
authors.initials: OK
authors.lastname: Doumbo
authors.forename: Amagana
authors.initials: A
authors.lastname: Dolo
authors.forename: Susan K
authors.initials: SK
authors.lastname: Pierce
authors.forename: Peter D
authors.initials: PD
authors.lastname: Crompton
mesh_terms: D000328:Adult; D001402:B-Lymphocytes / Q000276:immunology*; D003430:Cross-Sectional Studies; D004198:Disease Susceptibility; D005006:Ethnicity; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007958:Leukocyte Count; D016131:Lymphocyte Subsets / Q000276:immunology; D016778:Malaria, Falciparum / Q000276:immunology*; D008297:Male; D008302:Mali; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*; D014481:United States; D055815:Young Adult