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Open Access Research

Suppression of circulating IgD+CD27+ memory B cells in infants living in a malaria-endemic region of Kenya

Amolo S Asito12*, Erwan Piriou234, Walter GZO Jura1, Collins Ouma12, Peter S Odada2, Sidney Ogola12, Nancy Fiore3 and Rosemary Rochford3*

Author Affiliations

1 Maseno University, Maseno, Kenya

2 Center for Global Health Research, Kenya Medical Research Institute, Kisumu, Kenya

3 SUNY Upstate Medical University, Syracuse, NY, USA

4 Médecins Sans Frontières-Operational Centre Amsterdam, Amsterdam, The Netherlands

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Malaria Journal 2011, 10:362  doi:10.1186/1475-2875-10-362

Published: 13 December 2011

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.

Keywords:
B cells; Infant immunity; Plasmodium falciparum