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Abstract：
Emerging evidence started to delineate multiple layers of memory B cells, with distinct effector functions during recall responses. Whereas most studies examining long-lived memory B cell responses have focussed on the IgG+ memory B cell compartment, IgM+ memory B cells have only recently started to receive attention. It has been proposed that unlike IgG+ memory B cells, which differentiate into antibody-secreting plasma cells upon antigen re-encounter, IgM+ memory B cells might have the additional capacity to establish secondary germinal centre (GC) responses. The precise function of IgM+ memory B cells in the humoral immune response to malaria has not been fully defined. Using a murine model of severe malaria infection and adoptive transfer strategies we found that IgM+ memory B cells induced in responses to P. berghei ANKA readily proliferate upon re-infection and adopt a GC B cell-like phenotype. The results suggest that that IgM+ memory B cells might play an important role in populating secondary GCs after re-infection with Plasmodium, thereby initiating the induction of B cell clones with enhanced affinity for antigen, at faster rates than naive B cells.
摘要：
新出现的证据开始描绘多层记忆B细胞，在召回响应期间具有不同的效应器功能。然而，大多数研究长期记忆B细胞反应的研究都集中在IgG+记忆B细胞区室，IgM+记忆B细胞最近才开始受到关注。有人提出，与IgG+记忆B细胞不同，在抗原重新相遇后分化为分泌抗体的浆细胞，IgM+记忆B细胞可能具有建立次级生发中心(GC)应答的额外能力。尚未完全确定IgM记忆B细胞在对疟疾的体液免疫应答中的确切功能。使用严重疟疾感染的鼠模型和过继性转移策略，我们发现IgM记忆B细胞在对伯氏疟原虫ANKA的反应中诱导，在再次感染后容易增殖并采用GCB细胞样表型。结果表明，IgM+记忆B细胞可能在疟原虫再次感染后的继发性GCs中发挥重要作用。从而启动对抗原亲和力增强的B细胞克隆的诱导，比幼稚B细胞更快的速度。
