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B cell clones that sustain long-term plasmablast growth in T-independent extrafollicular antibody responses.

ABSTRACT: Some antigens induce Ab responses without T lymphocyte help. Among these, many polysaccharide-based antigens cause marginal zone B cells to proliferate and differentiate into plasma cells. B1 cells also respond to some of these antigens. In this article, we report that antigen-specific B1b cells, in response to the T-independent antigen (4-hydroxy-3-nitrophenyl)-acetyl (NP)-Ficoll, develop into clones that sustain Ab production for months with continued production of plasma cells and the accumulation of antigen-specific B cells in follicles. The persistence of this T-independent plasmablast response contrasts with the short-term plasmablast growth associated with T-dependent extrafollicular responses. The nature of the cells responding to NP-Ficoll was probed by using chimeras that have B1 cells but lack primary B lymphopoietic capacity and have very few B2 cells or T cells. The chimeras were constructed by transferring 10(5) IgM(+) IgD(-) peritoneal exudate cells into mice unable to produce their own T and B cells because of deficiency in recombinase-activating gene 1 (RAG-1). The chimeras mounted sustained IgM and IgG3 anti-NP Ab responses to NP-Ficoll. This finding was associated with continued NP-specific extrafollicular plasmablast growth and the accumulation of NP-specific B cells in follicles. B cells were not found in the marginal zones of chimeras, and they also lacked recirculating IgD(+) cells and CD3(+) cells. The absence of B2 and T cells confirms that hemopoietic cell chimerism leading to primary lymphopoiesis had not been established.

SUBMITTER: Hsu MC

PROVIDER: S-EPMC1424660 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:The normal response to influenza A infection is to remain asymptomatic; indeed, a study of volunteers who tested positive for antibodies against 2009 H1N1 revealed that a majority did not experience symptoms. However, studies of influenza pandemics since the 20th century, and to a lesser degree seasonal flu, suggest that pregnancy increases influenza-associated morbidity and mortality. The confounding effect of pregnancy has been well established to adversely alter the clinical course of influenza, with short term complications to mother and baby apparent, and long-term consequences to the fetus hypothesized. However, how the condition of pregnancy impacts long-term maternal anti-influenza immunity remains contentious; while vaccination studies suggest humoral responses sufficient for protection, published research on adaptive immune responses against influenza formed during pregnancy is limited. This study expands upon published work from our lab and others by comprehensively examining compartmental and systemic changes following pandemic A/California/07/2009 influenza infection. Previously, we linked seasonal influenza infection to clinical observations of adverse outcomes in pregnancy, enhanced lung and placental histopathology, and reduced control of viral replication in lungs of infected pregnant mothers. Here, we observe that the results of a lower infectious dose of pandemic influenza are similar to that of seasonal influenza. Importantly, we expand upon work which suggests infection during pregnancy may also affect humoral immunity. Our observations of reduced early antibody hemagglutinin inhibition and virus neutralization which resolved within 8 weeks of delivery demonstrate that influenza infection impacts antibody maturation mechanisms without alterations to B cell frequency or antibody secretion. This hypothesis is further supported by plasmablast transcriptional data, which demonstrates downregulated B cell metabolism and post-translational modification systems only among pregnant animals. These findings corroborate a link between adverse pregnancy outcomes and severe pathology observed during influenza infection, and propose resolving humoral deficiencies following influenza infection confounded by pregnancy. Additional studies are required to specify the involvement of plasmablast metabolism with early humoral immunity abnormalities to best guide vaccination strategies and improve our understanding of the immunological consequences of pregnancy.

Project description:Whether marine fish will grow differently in future high pCO2 environments remains surprisingly uncertain. Long-term and whole-life cycle effects are particularly unknown, because such experiments are logistically challenging, space demanding, exclude long-lived species, and require controlled, restricted feeding regimes-otherwise increased consumption could mask potential growth effects. Here, we report on repeated, long-term, food-controlled experiments to rear large populations (>4,000 individuals total) of the experimental model and ecologically important forage fish Menidia menidia (Atlantic silverside) under contrasting temperature (17°, 24°, and 28°C) and pCO2 conditions (450 vs. ~2,200 μatm) from fertilization to ~ a third of this annual species' life span. Quantile analyses of trait distributions showed mostly negative effects of high pCO2 on long-term growth. At 17°C and 28°C, but not at 24°C, high pCO2 fish were significantly shorter [17°C: -5 to -9%; 28°C: -3%] and weighed less [17°C: -6 to -18%; 28°C: -8%] compared to ambient pCO2 fish. Reductions in fish weight were smaller than in length, which is why high pCO2 fish at 17°C consistently exhibited a higher Fulton's k (weight/length ratio). Notably, it took more than 100 days of rearing for statistically significant length differences to emerge between treatment populations, showing that cumulative, long-term CO2 effects could exist elsewhere but are easily missed by short experiments. Long-term rearing had another benefit: it allowed sexing the surviving fish, thereby enabling rare sex-specific analyses of trait distributions under contrasting CO2 environments. We found that female silversides grew faster than males, but there was no interaction between CO2 and sex, indicating that males and females were similarly affected by high pCO2. Because Atlantic silversides are known to exhibit temperature-dependent sex determination, we also analyzed sex ratios, revealing no evidence for CO2-dependent sex determination in this species.

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B cell clones that sustain long-term plasmablast growth in T-independent extrafollicular antibody responses.

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