<p>Continuous exposure to <i>Plasmodium falciparum</i> (Pf) has been associated with alterations in B cells. We investigated the effect of controlled human malaria infection (CHMI) on B cell phenotypes in individuals with different Pf immunity status: malaria-naïve, immunized with PfSPZ-CVac and semi-immune (lifelong-exposed) volunteers. Compared to naïve, semi-immune but not vaccinated individuals, had increased baseline frequencies of immature B cells (CD19<sup>+</sup>CD10<sup>+</sup>), active naive (IgD<sup>+</sup>CD27<sup>−</sup>CD21<sup>−</sup>) B cells, active atypical (IgD<sup>−</sup>CD27<sup>−</sup>CD21<sup>−</sup>) memory B cells (MBCs), active classical (IgD<sup>−</sup>CD27<sup>+</sup>CD21<sup>−</sup>) MBCs and CD1c<sup>+</sup>-B cells but lower frequencies of some IgG<sup>+</sup>-B cells. The frequencies of CD1c<sup>+</sup> active atypical MBCs correlated positively with anti-Pf antibodies and negatively with circulating eotaxin levels, while the opposite was observed for IgG<sup>+</sup> resting atypical MBCs. During early blood-stage infection (day 11 after CHMI), there was an expansion of resting classical (IgD<sup>−</sup>CD27<sup>+</sup>CD21<sup>+</sup>) MBCs in all three groups. Vaccination, compared to placebo, altered the effect of CHMI on B cells, showing a positive association with resting classical MBCs (β = 0.190, 95% CI 0.011–0.368) and active naïve-PD1<sup>+</sup> (β = 0.637, 95% CI 0.058 to 1.217) frequencies, and a negative one with CD1c<sup>+</sup> resting atypical MBCs (β = − 0.328, 95% CI − 0.621 to − 0.032). In addition, the sickle cell trait in semi-immune subjects altered the effect of CHMI on several B cells. In conclusion, lifelong but not vaccine exposure to malaria was associated with increased frequencies of multiple B cell subsets, with higher and lower percentages of CD1c and IgG expressing-cells, respectively. A single infection (CHMI) induces changes in B cell frequencies and is modulated by sickle cell trait and malaria-immunity status.</p><p><i>Clinical Trials Registration</i> NCT01624961, NCT02115516, and NCT02237586.</p>

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Effect of controlled human Plasmodium falciparum infection on B cell subsets in individuals with different levels of malaria immunity

  • Pilar Requena,
  • Gloria Patricia Gómez-Pérez,
  • Matthew B. B. McCall,
  • Diana Barrios,
  • Ruth Aguilar,
  • Julia Fernández-Morata,
  • Marta Vidal,
  • Joseph J. Campo,
  • Carla Sanchez,
  • Maria Yazdabankhsh,
  • B. Kim Lee Sim,
  • Stephen L. Hoffman,
  • Peter Kremsner,
  • Bertrand Lell,
  • Benjamin Mordmüller,
  • Carlota Dobaño,
  • Gemma Moncunill

摘要

Continuous exposure to Plasmodium falciparum (Pf) has been associated with alterations in B cells. We investigated the effect of controlled human malaria infection (CHMI) on B cell phenotypes in individuals with different Pf immunity status: malaria-naïve, immunized with PfSPZ-CVac and semi-immune (lifelong-exposed) volunteers. Compared to naïve, semi-immune but not vaccinated individuals, had increased baseline frequencies of immature B cells (CD19+CD10+), active naive (IgD+CD27CD21) B cells, active atypical (IgDCD27CD21) memory B cells (MBCs), active classical (IgDCD27+CD21) MBCs and CD1c+-B cells but lower frequencies of some IgG+-B cells. The frequencies of CD1c+ active atypical MBCs correlated positively with anti-Pf antibodies and negatively with circulating eotaxin levels, while the opposite was observed for IgG+ resting atypical MBCs. During early blood-stage infection (day 11 after CHMI), there was an expansion of resting classical (IgDCD27+CD21+) MBCs in all three groups. Vaccination, compared to placebo, altered the effect of CHMI on B cells, showing a positive association with resting classical MBCs (β = 0.190, 95% CI 0.011–0.368) and active naïve-PD1+ (β = 0.637, 95% CI 0.058 to 1.217) frequencies, and a negative one with CD1c+ resting atypical MBCs (β = − 0.328, 95% CI − 0.621 to − 0.032). In addition, the sickle cell trait in semi-immune subjects altered the effect of CHMI on several B cells. In conclusion, lifelong but not vaccine exposure to malaria was associated with increased frequencies of multiple B cell subsets, with higher and lower percentages of CD1c and IgG expressing-cells, respectively. A single infection (CHMI) induces changes in B cell frequencies and is modulated by sickle cell trait and malaria-immunity status.

Clinical Trials Registration NCT01624961, NCT02115516, and NCT02237586.