Malaria-induced interferon-γ drives the expansion of Tbethi atypical memory B cells

by Nyamekye Obeng-Adjei, Silvia Portugal, Prasida Holla, Shanping Li, Haewon Sohn, Abhijit Ambegaonkar, Jeff Skinner, Georgina Bowyer, Ogobara K. Doumbo, Boubacar Traore, Susan K. Pierce, Peter D. Crompton

Many chronic infections, including malaria and HIV, are associated with a large expansion of CD21⁻CD27⁻ 'atypical' memory B cells (MBCs) that exhibit reduced B cell receptor (BCR) signaling and effector functions. Little is known about the conditions or transcriptional regulators driving atypical MBC differentiation. Here we show that atypical MBCs in malaria-exposed individuals highly express the transcription factor T-bet, and that T-bet expression correlates inversely with BCR signaling and skews toward IgG3 class switching. Moreover, a longitudinal analysis of a subset of children suggested a correlation between the incidence of febrile malaria and the expansion of T-bet^hi B cells. The Th1-cytokine containing supernatants of malaria-stimulated PBMCs plus BCR cross linking induced T-bet expression in naïve B cells that was abrogated by neutralizing IFN-γ or blocking the IFN-γ receptor on B cells. Accordingly, recombinant IFN-γ plus BCR cross-linking drove T-bet expression in peripheral and tonsillar B cells. Consistent with this, Th1-polarized Tfh (Tfh-1) cells more efficiently induced T-bet expression in naïve B cells. These data provide new insight into the mechanisms underlying atypical MBC differentiation.

from # All Medicine by Alexandros G. Sfakianakis via Alexandros G.Sfakianakis on Inoreader http://ift.tt/2xB72l5
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