A splenic IgM memory subset with antibacterial specificities is sustained from persistent mucosal responses

Abstract

Le Gallou et al. use an AID fate-mapping model to identify an IgM memory population in the spleen of unimmunized mice, originating from persistent gut immune responses and endowed with cross-reactivity against bacteria.

Microbiota-targeted maternal antibodies protect neonates from enteric infection

“…Beyond antigens shared by specific bacterial groups (for example, lipopolysaccharides of Gram-negative bacteria), some antigens can be expressed by diverse and phylogenetically distant bacterial species, including commensal microorganisms 28 . Moreover, poly-reactive IgM can recognize both pathogenic and commensal bacteria and affords some protection against pathogen challenge in mice 29 . Thus, our study indicates that modulation of the maternal microbiota to optimize the induction of cross-reactive antibodies that are protective against important neonatal pathogens should be explored.…”

Anti-CD20–mediated B-cell depletion in autoimmune diseases: successes, failures and future perspectives

“…43 No GC or marginal zoneresistant B cells were observed, contrasting with results obtained with several mouse strains. [53][54][55][56] These findings highlight that mouse models of anti-CD20 depletion cannot be extrapolated to humans, probably because of different Fc receptors and effector cell mobilization. 57 Several groups have described the persistence of CD19 þ CD27 þ IgD À memory B cells in lymph nodes from patients obtained 1 month after a single dose of RTX (500 mg) given for prevention of antibody-mediated rejection.…”

The microbiome and immune memory formation

“…The ability of the mucosal immune system to co‐operate with systemic immunity in a homeostatic context is further highlighted by increased levels of T‐dependent serum IgA in response to certain commensals in the gut and induction of IgA‐secreting plasma cells in the bone marrow . Furthermore, clonal relationships between gut IgA plasma cells and memory cells in the spleen as well as splenic IgM memory subsets with antibacterial specificities sustained from persistent mucosal responses have been described . Moreover, antibodies derived from FCLR4‐expressing memory B cells recognizing commensal microbial antigens have been identified in tonsils of healthy individuals .…”

“…24 Furthermore, clonal relationships between gut IgA plasma cells and memory cells in the spleen as well as splenic IgM memory subsets with antibacterial specificities sustained from persistent mucosal responses have been described. 14,25 Moreover, antibodies derived from FCLR4-expressing memory B cells recognizing commensal microbial antigens have been identified in tonsils of healthy individuals. 26 Although the small intestine represents the predominant site of IgA production, IgA-secreting plasma cells are also found in lactating mammary glands.…”