Biology subjects

Tipton, C. M.

Publications and source records attributed to Tipton, C. M..

3 recordsLinked to original sources

bioRxiv2021

Atypical B cells upregulate co-stimulatory molecules during malaria and secrete antibodies with T follicular helper cell support

Several infectious and autoimmune diseases are associated with an expansion of CD21-CD27- atypical B cells (atBCs). The function of atBCs remains unclear and few studies have investigated the biology of pathogen-specific atBCs during acute infection. Here, we performed longitudinal RNA-sequencing and flow cytometry analyses of Plasmodium falciparum (Pf)-specific B cells before and shortly after febrile malaria, with simultaneous analysis of influenza hemagglutinin (HA)-specific B cells as a comparator. B cell receptor-sequencing showed that Pf-specific atBCs, activated B cells (actBCs) and classical memory B cells share clonality and have comparable somatic hypermutation. In response to malaria, Pf-specific atBCs and actBCs expanded and upregulated molecules that mediate B-T cell interactions, suggesting that atBCs respond to T follicular helper (Tfh) cells. Indeed, in the presence of Tfh cells and Staphylococcal enterotoxin B, atBCs of malaria-exposed individuals differentiated into CD38+ antibody-secreting cells in vitro, suggesting that atBCs may actively contribute to humoral immunity to infectious pathogens. One Sentence SummaryThis study shows that atypical B cells actively respond to acute malaria and have the capacity to produce antibodies with T cell help.

immunology↗

bioRxiv2020

Plasmodium falciparum-specific IgM B cells dominate in children, expand with malaria and produce parasite inhibitory IgM

IgG antibodies are known to play a central role in naturally acquired immunity to blood-stage malaria in humans, but little is known about the IgM response to blood-stage malaria, the mechanisms by which IgM may protect, or the underlying biology of Plasmodium falciparum (Pf)-specific IgM B cells. In a Mali cohort spanning infants to adults we conducted a longitudinal analysis of B cells specific for the Pf blood-stage antigens AMA1 and MSP1, as well as the comparator antigen influenza hemagglutinin (HA). At the uninfected baseline, before the malaria season, Pf-specific memory B cells (MBCs) in children are disproportionally IgM+ and only gradually shift to IgG+ with age, in contrast to HA-specific MBCs that are predominantly IgG+ from infancy to adulthood. In response to acute febrile malaria, Pf-specific IgM B cells increase in frequency and upregulate activation and co-stimulatory markers. B cell receptor (BCR) analysis showed that Pf-specific IgM B cells are somatically hypermutated at levels comparable to HA-specific IgG B cells. Finally, IgM antibodies from the plasma of malaria-exposed individuals were comparable to IgG in inhibiting Pf blood-stage growth in vitro, and significantly better at enhancing phagocytosis of Pf merozoites, suggesting that IgM may protect through both direct neutralization and opsonization. Thus, somatically hypermutated Pf-specific IgM MBCs dominate in early life, are activated and expand during acute malaria and are associated with plasma IgM that inhibits parasite growth in vitro.

immunology↗

bioRxiv2019

Fcrl5 and T-bet define influenza-specific memory B cells that predict long-lived antibody responses

Seasonal influenza vaccination elicits hemagglutinin (HA)-specific CD27+ memory B cells (Bmem) that differ in expression of T-bet, BACH2 and TCF7. T-bethiBACH2loTCF7lo Bmem are transcriptionally similar to effector-like memory cells while T-betloBACH2+TCF7+ Bmem exhibit stem-like central memory properties. T-bethi Bmem do not express plasma cell-specific transcription factors but do exhibit transcriptional, epigenetic, metabolic and functional changes that poise the cells for antibody production. Consistent with these changes, D7 HA+ T-bethi Bmem express intracellular immunoglobulin and T-bethi Bmem differentiate more rapidly into ASCs in vitro. The T-bethi Bmem response positively correlates with long-lived humoral immunity and clonotypes from T-bethi Bmem are represented in the early secondary ASC response to repeat vaccination, suggesting that this effector-like population can be used to predict vaccine durability and recall potential.

immunology↗