BAFF and BAFF receptor levels correlate with B cell subset activation and redistribution in controlled human malaria infection

A Scholzen, AC Teirlinck, EM Bijker… - The Journal of …, 2014 - journals.aai.org
A Scholzen, AC Teirlinck, EM Bijker, M Roestenberg, CC Hermsen, SL Hoffman
The Journal of Immunology, 2014journals.aai.org
Characteristic features of Plasmodium falciparum malaria are polyclonal B cell activation
and an altered composition of the blood B cell compartment, including expansion of CD21−
CD27− atypical memory B cells. BAFF is a key cytokine in B cell homeostasis, but its
potential contribution to the modulation of the blood B cell pool during malaria remains
elusive. In the controlled human malaria model (CHMI) in malaria-naive Dutch volunteers,
we therefore examined the dynamics of BAFF induction and B cell subset activation and …
Abstract
Characteristic features of Plasmodium falciparum malaria are polyclonal B cell activation and an altered composition of the blood B cell compartment, including expansion of CD21− CD27− atypical memory B cells. BAFF is a key cytokine in B cell homeostasis, but its potential contribution to the modulation of the blood B cell pool during malaria remains elusive. In the controlled human malaria model (CHMI) in malaria-naive Dutch volunteers, we therefore examined the dynamics of BAFF induction and B cell subset activation and composition, to investigate whether these changes are linked to malaria-induced immune activation and, in particular, induction of BAFF. Alterations in B cell composition after CHMI closely resembled those observed in endemic areas. We further found distinct kinetics of proliferation for individual B cell subsets across all developmental stages. Proliferation peaked either immediately after blood-stage infection or at convalescence, and for most subsets was directly associated with the peak parasitemia. Concomitantly, plasma BAFF levels during CHMI were increased and correlated with membrane-expressed BAFF on monocytes and dendritic cells, as well as blood-stage parasitemia and parasite-induced IFN-γ. Correlating with increased plasma BAFF and IFN-γ levels, IgD− CD38 low CD21− CD27− atypical B cells showed the strongest proliferative response of all memory B cell subsets. This provides unique evidence for a link between malaria-induced immune activation and temporary expansion of this B cell subset. Finally, baseline BAFF-R levels before CHMI were predictive of subsequent changes in proportions of individual B cell subsets. These findings suggest an important role of BAFF in facilitating B cell subset proliferation and redistribution as a consequence of malaria-induced immune activation.
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