bluuebunny/crossref_metadata_2025_split huggingface dataset:
Herpesvirus latency differentially impacts primary versus secondary memory T cell pools (P6119)
Authors: Grayson Jason , Jennings Ryan , Rajkarnikar Sujana , Barton Erik 
Published: January 2023

Abstract
Unlike laboratory animals, humans are infected with multiple pathogens, including the highly prevalent herpesviruses. The purpose of these studies was to determine the effect of herpesvirus latency on T cell number and differentiation during subsequent heterologous viral infections. Mice were infected with murine Gammaherpesvirus 68 (MHV68), a model of Epstein-Barr infection, and then after latency was established, infected with the Armstrong strain of lymphocytic choriomeningitis virus (LCMV). This resulted in increased LCMV-specific effector CD4+ T cells compared to mice infected only with LCMV. Although the number of LCMV-specific effector CD8+ T cells was not altered, they were skewed to a memory phenotype. When the memory phase was reached, mice that were infected with both viruses had a memory T cell pool that was increased relative to that found in singly infected mice. Importantly, LCMV-specific memory CD8+ T cells had altered CD27 and KLRG1 expression. Upon secondary challenge the LCMV-specific effector CD8+ and CD4+ T cell pools expanded and cleared the infection. When the secondary memory pool was established, mice that were also infected with MHV68 had decreased numbers of LCMV-specific CD8+ T cells and these cells were skewed to an effector-memory phenotype. Taken together these results demonstrate that acute viral infection in the context of ongoing latency affects the number and phenotype of primary versus secondary memory CD8+ T cells.
Function and regulation of human NK cells in an acute viral infection model (P6127)
Authors: Marquardt Nicole , Ivarsson Martin , Blom Kim , Braun Monika , Gonzalez Veronica , Falconer Karolin , Sandberg Johan , Michaelsson Jakob 
Published: January 2023

Abstract
Natural killer (NK) cells play an important role in shaping the immune response by releasing proinflammatory cytokines and direct lysis of malignant or virus-infected cells. However, very little is known about the earliest phases of the human NK cell response after acute infection in vivo. Here we made use of the yellow fever virus (YFV) vaccine strain 17D as an in vivo model of an acute viral infection in humans. Vaccination with the live attenuated 17D yellow fever strain induces a measurable viral load and strong T cell activation. YFV vaccination activated NK cells in vivo with distinct kinetics for different functions. NK cell activation as measured by upregulation of Ki67 peaked at day 10, whereas increased degranulation and cytokine production by NK cells peaked at day 6, and coincided with a peak in type I interferons and viral load. Interestingly, within the CD56dim NK cell population, activation was strongest in the least differentiated subset, but was independent of NK cell education via killer cell Ig-like receptors (KIRs). In conclusion, vaccination with 17D allows a detailed longitudinal analysis of NK cell activation after an acute viral infection in humans, and reveals a hierarchy of activation among different NK cell subsets.
Severely exhausted CD8 T cells are refractory to rescue by PD-1 blockade, but re-invigorate following concomitant CD4 T cell depletion in vivo (P6097)
Authors: Penaloza-MacMaster Pablo , Barouch Dan 
Published: January 2023

Abstract
Blockade of the inhibitory PD-1 receptor during chronic infections and cancers has been promising at restoring CD8 T cell function, but it is currently unknown if this functional rescue is optimal during a specific stage of the process of T cell exhaustion. In a model of lifelong LCMV infection in mice, we showed that there is an early phase when PD-1 blockade is able to induce robust rescue of exhausted CD8 T cell responses. As the infection progresses, however, most of the severely exhausted cells become refractory to rescue by PD-1 blockade. This indicated a continuous accumulation of more terminally differentiated virus-specific T cells that underwent a T cell exhaustion program that was regulated by additional inhibitory pathways. This progressive decrease in CD8 T cell rescue potential was associated with a gradual increase in CD4+ Tregs. Interestingly, PD-1 blockade together with transient CD4 depletion during the late stage of chronic infection was able to re-invigorate severely exhausted CD8 T cells and enhance antiviral control. Importantly, whole CD4 depletion did not result in fulminant autoimmune-mediated death that is typically observed following specific Treg ablation. These data suggest that a crucial interplay exists between the PD-1 pathway and CD4+ Tregs at modulating CD8 T cell exhaustion. Our findings may also help to improve immune prophylaxis regimens in patients who remain refractory to PD-1 blockade therapy during chronic infections and cancer.
DNAM-1 is required for expansion of effector NK cells and generation of memory NK cells during mouse cytomegalovirus infection (P6100)
Authors: Nabekura Tsukasa , Lanier Lewis 
Published: January 2023

Abstract
Recent studies have demonstrated that natural killer (NK) cells have adaptive immune features including antigen-specific expansion and subsequent generation of a memory subset. However, the precise signaling pathways that promote the expansion and the generation of memory NK cells remain to be elucidated. Using mixed bone marrow chimeric mice, we investigated the role of DNAM-1, an activating NK cell receptor, in expansion and memory generation of NK cells in a mouse model of cytomegalovirus infection (MCMV). We demonstrated that DNAM-1-deficient MCMV-specific Ly49H+ NK cells exhibit not only a poor expansion following MCMV infection, but also defects in both memory NK cell generation and secondary expansion after re-challenge with MCMV, as compared with wild type Ly49H+ NK cells. The frequency of DNAM-1- NK cells bearing Ly49H gradually increase and the long-lived Ly49H+ NK cells do not express DNAM-1 in MCMV-infected wild type mice. Interestingly, DNAM-1-Ly49H+ effector NK cells are more proliferative and less sensitive to cell death than DNAM-1+Ly49H+ NK cells during MCMV infection. These observations suggest that cooperative signaling through DNAM-1 and Ly49H induces downmodulation of DNAM-1 on Ly49H+ NK cells, resulting in predominant expansion and persistence of DNAM-1-Ly49H+ NK cells during MCMV infection. Therefore, DNAM-1 is a key molecule for optimal effector response and memory generation of virus-specific NK cells.
Disruption of folliculin interacting protein-1 inhibits Myc-driven glycolysis and sensitizes B cells to apoptosis following activation and chemotherapy. (P1455)
Authors: Ramirez Julita , Tsang Mark , Margineantu Daciana , Hockenbery David , Iritani Brian 
Published: January 2023

Abstract
Folliculin interacting protein-1 (Fnip1) is a cytoplasmic protein originally discovered through its interaction with Folliculin (Flcn), a tumor suppressor mutated in the hamartoma disorder Birt-Hogg Dubé syndrome. Fnip1 and Flcn both interact with the master metabolic regulator AMPK. Our previous studies have shown that Fnip1 is required for the development of B-cells past the late pre-B stage. Fnip1 deficiency also prevented the development of pre-B cell lymphoma in Eµ-Myc transgenic mice. In this study, we examined the potential efficacy of Fnip1 inhibition in cancer and autoimmunity treatments by disrupting Fnip1 expression in B lymphoma cells and activated IgM-expressing B cells. We show that siRNA-mediated depletion of endogenous FNIP1 from a human B cell line expressing a conditional Myc allele increases oxidative phosphorylation in a glutamine-dependent manner and decreases Myc-induced glycolysis, which supports cell division (Warburg Effect). Disruption of Fnip1 also reduces Myc-induced glycolysis and increases apoptosis of murine pre-B Eµ-Myc cells in response to nutrient deprivation and chemotherapeutic drugs ex vivo. Fnip1 deficient B cells expressing an IgMHEL transgene exhibit a “tolerant” phenotype and exhibit increased sensitivity to apoptosis following BCR crosslinking. These results suggest that inhibition of Fnip1 may provide a novel strategy to sensitize lymphoma cells to apoptosis, and/or tolerize or delete activated B cells in autoimmune diseases.
B lymphocyte-induced maturation protein-1 (Blimp-1) maintains plasma cell survival by directly suppressing apoptosis signal-regulating kinase 1 (ASK1) (P1463)
Authors: Lin Kuo-I , Lin Fan-Ru 
Published: January 2023

Abstract
Terminally differentiated, antibody-secreting plasma cells are the end-stage effectors of humoral immune responses. Understanding the regulatory mechanisms that maintain the longevity of plasma cells provides a rational basis for designing strategies to enhance the levels of vaccine-induced antibodies. Blimp-1 orchestrates plasma cell differentiation by silencing the gene expression program of mature B cells. We showed that long-lived plasma cells in the bone marrow require the continuous presence of Blimp-1. Inhibition of Blimp-1 in plasma cells caused apoptosis. We performed microarray study examining the differential gene expression following depletion of Blimp-1 in plasma cells and uncovered that Blimp-1 suppresses apoptosis signal-regulating kinase 1 (ASK1). Blimp-1 directly suppresses ASK1 transcription. Knocking down ASK1 and Blimp-1 together in plasma cells blocked Blimp-1 knockdown-mediated apoptosis. Furthermore, ASK1 plays a negative role in survival of long-lived and short-lived plasma cells. ASK1 activity was induced during differentiation of short-lived plasma cells, and when produced by ASK1-deficient mice these cells survived better than those of control mice. Similarly, antigen-specific long-lived plasma cells generated by immunization accumulated in ASK1-deficient mice. Given that ASK1 induces apoptosis in response to stress, we rationalized that long-lived plasma cells may require sustained suppression of ASK1 by Blimp-1 to maintain survival.
Role of heterotrimeric G-protein exchange factor Ric-8A in B cell development and asymmetric cell division (P1465)
Authors: Boularan Cedric , Kehrl John 
Published: January 2023

Abstract
B lymphocytes likely divide asymmetrically to generate different effector and memory lymphocytes subsets. Studies in C. Elegans have shown that Resistance to inhibitors of cholinesterase (Ric)-8A helps orient the mitotic spindle during asymmetric cell division. However, the role of Ric-8A in lymphocytes development and function during asymmetric cell division is unknown. We have used a mouse strain carrying the Cre recombinase under the control of vav1 promoter or Mb1 promoter to specifically delete a floxed Ric-8a allele in all hematopoietic cells or specifically in B lymphocytes. As Ric-8A is a molecular chaperone for the Gα proteins, we first verified that Ric-8A deletion was correlated with a physical and functional loss of Gαi and Gαq proteins. As only the absolute number of B220+ cells was reduced in lymphoid organs (mostly the marginal zone B cells and T2-B subsets) we focused on the BCR signaling. Ric-8A deletion leads to an altered production of antibodies and defect in calcium response towards IgM stimulation. The simultaneously visualization of the ancestral polarity network member PKCζ with B220 distributions revealed that Ric-8A KO B-cells are less susceptible to asymmetric fate than the WT cells [ImageStream (AMNIS)]. While the molecular mechanisms leading to this phenotype are under investigation, these results indicate that Ric-8A is important for the expansion and/or differentiation of B cells by regulating the asymmetric cell division properties.
CD28 signaling in long lived plasma cells regulates glycolysis for survival and antibody production. (P1469)
Authors: Utley Adam , Carlson Louise , Murray Megan , Lee Kelvin 
Published: January 2023

Abstract
Recent evidence suggests that sustained humoral immunity is dependent upon bone marrow resident long-lived antibody secreting plasma cells (LLPCs). However, the signaling pathways that define LLPC survival and function are not completely understood. We have shown that CD28 signaling in LLPCs is necessary for their survival and sustained antibody production. In T cells, CD28 is known to regulate the induction of glycolysis during activation. What is unclear is how CD28 may regulate metabolism in plasma cells. It is also recognized that many of the molecular pathways governing LLPC cell survival are also observed in multiple myeloma, the transformed counterpart of plasma cells. Here we demonstrate that CD28-mediated signaling induces glut1 expression and that poisoning glycolysis inhibits proliferation and antibody production in both plasma cells and multiple myeloma cells. Interestingly, inhibition of glycolysis inactivates AMPK, a major metabolic sensor responsible for facilitating fatty acid oxidation (FAO). Furthermore, induction of AMPK by AICAR could not rescue the defects induced by glycolytic inhibition, suggesting that LLPCs require CD28-mediated glycolytic end products for both biosynthesis and oxidative energy production. By understanding the metabolic regulation of plasma cell induction, maintenance, and function, we may find insight into how targeting metabolism may alter both long-term humoral immunity and how we can use this knowledge to treat multiple myeloma.
HIV triggers interleukin 21-mediated induction of granzyme B-secreting B cells with T cell regulatory potential. (P1441)
Authors: Jahrsdörfer Bernd , Kaltenmeier Christof , Gawanbacht Ali , Lindner Stefanie , Beyer Thamara , Härter Georg , Grüner Beate , Kern Peter , Kirchhoff Frank , Schrezenmeier Hubert 
Published: January 2023

Abstract
Certain regulatory lymphocyte subpopulations like regulatory T cells can suppress T cell expansion by granzyme B (GrB) secretion. Recently, we found that B cells can also produce GrB and acquire regulatory potential in response to interleukin (IL-)21. Since HIV is associated with elevated serum IL-21 levels, we hypothesized that GrB-expressing B cells may be induced during HIV infection. Here, we show that infection of CD4+ T cells with HIV 1 (NL4-3) induces strong expression of IL-21 without upregulation of CD40 ligand. We demonstrate that such IL-21+CD40Llow T cells secrete IL-21, thereby inducing GrB in cocultured B cells rather than supporting plasma cell differentiation. In line with these results, serum levels of both IL-21 and GrB are significantly higher in HIV-infected patients before HAART as compared to healthy controls. Up to 60% of freshly isolated B cells from HIV-infected patients, but not healthy control B cells, express GrB. Of note, coculture of HIV-infected CD4+ T cells with GrB+ B cells results in GrB transfer, and strongly suppresses both T cell proliferation and viral replication as indicated by significantly reduced p24 levels. The observed effects are enhanced by IL-21, and reduced by GrB inhibition. In summary, GrB induction in HIV-specific B cells may play a role in decelerating expansion of HIV-infected CD4+ T cells, while interfering with their terminal differentiation into plasma cells.
The role of Bcl6 in the regulation of transitional B cells and resting mature B cells (P1449)
Authors: Wu Hao , Hollister Kristin , Dent Alexander 
Published: January 2023

Abstract
As a conserved zinc finger transcription repressor, Bcl6 determines follicular helper T cell differentiation and plays indispensible roles in B cell development and function, especially at the stages of pre-B cell and germinal center B cell. To better understand the role of Bcl6 in B cell lineage, we generate Bcl6 conditional KO mouse by crossing Bcl6 floxed mouse newly made in our lab to CD19cre mouse. Interestingly, B cell development in the bone marrow of conditional KO mice is indistinguishable from control mice. At the transition of T1 B cell to T2 B cell stage, Bcl6 is upregulated and continually maintained in mature B cells. Mainly because of a significant decrease of follicular B cell, conditional KO mice have significantly fewer B220+ cells in spleen compared to control mice. Furthermore, in conditional KO mice, spontaneously-formed GCB cells in Peyer’s patches are decreased dramatically, but there is only slight reduction of GCB cells in spleen after SRBC immunization. The GCB cells in spleen appear to be from incomplete deletion of Bcl6 by CD19cre and by strong proliferation of non-deleted GCB cells. Finally and surprisingly, we detect “truncated Bcl6” in non-GCB cells from Peyer’s patches and spleen in conditional KO mice, which is four times higher than WT Bcl6 in control mice. This indicates an autorepression regulation of Bcl6 in resting mature B cells. Our findings suggest that Bcl6 regulates transitional B cell maturation and maintenance of mature B cell.
IL-22 receptor-expressing stromal cells are located in the germinal center dark zone (P1451)
Authors: Siegers Y. , Reijmers Rogier , Papazian Natalie , Cupedo Tom 
Published: January 2023

Abstract
After antigen encounter and subsequent T cell-mediated B cell activation, germinal centers are formed within B cell follicles of lymph nodes giving rise to high affinity antibody secreting plasma cells and memory cells. Germinal centers are typically divided into a dark zone and light zone in which proliferation, class switching, affinity maturation and selection of B cells takes place. Stromal cells in the light zone are mainly follicular dendritic cells which are important in selection of high affinity B cells through presentation of immune complexes. On the other hand, dark zone stromal cells are still poorly defined. In search for novel markers to identify dark zone stroma we observed expression of IL-22R on stromal cells in the germinal center dark zone 10 days after immunization with TNP-KLH. Flow cytometric analysis confirmed that the IL-22R was expressed by an unidentified CD31-podoplanin- stromal cell subset within lymph nodes and that expression of the IL-22R was only detected after immunization. To understand the signals involved in the induction of IL-22R expression we set up an in vitro culture system of primary human stromal cells. Stimulation of these stromal cells with activated B cell-derived cytokines indicated that IL-22R expression could be controlled by TNF-α. These data suggest that IL-22R may be used as a novel marker for dark zone stromal cells and allow for speculations on a possible role for IL-22R signaling in germinal center reactions.
Blurring of the distinction between hemophagocytic lymphohistiocytosis and macrophage activation syndrome (P3307)
Authors: Cron Randy , Zhang Mingce 
Published: January 2023

Abstract
Hemophagocytic lymphohistiocytosis (HLH) is a fatal disorder of infancy resulting from homozygous mutations in cytolytic pathway proteins [MUNC13-4, RAB27A, PRF1, STX11, STXBP2]. Secondary HLH, or macrophage activation syndrome (MAS), results beyond infancy from rheumatologic, infectious, and oncologic conditions. We screened 21 children with MAS and identified 13 with mutations in 1 of the HLH genes. Three mutations [RAB27A (A87P), PRF1 (A91V), STXBP2 (A433V)] were studied for their effect on NK cell lytic activity. Lentiviral expression vectors were generated with wild-type (WT) or specific gene mutations, sequenced, and introduced into NK-92 cells. Transduction of WT RAB27A into NK-92 had no effect on cytolysis of K562 cells, whereas the mutation decreased cytolytic activity by ~50%. Both the PRF1 and STXBP2 mutants inhibited cytolysis to lesser degrees. The RAB27A mutant, but not the PRF1 or STXBP2 mutants, inhibited degranulation (diminished CD107a upregulation). All 3 mutants had no effect on intracellular perforin or granzyme B levels, or on conjugate formation with target cells. Confocal microscopy revealed the RAB27A mutant disrupted granzyme B polarization to the immunologic synapse. The data suggests single copy HLH gene mutations can partially disrupt cytolytic activity via a dominant negative effect, thus, blurring the genetic distinction between HLH and MAS.
Phenotypic analysis of B cell subsets in HLA*B44 positive identical twins discordant for common variable immunodeficiency and recurrent sino-pulmonary infection (P3331)
Authors: Szymanska Mroczek Ewa , Ippolito Gregory , Zemlin Michael , Hwangpo Tracy , Brand Marsha , Zhuang Yingxin , Crossman David , Osborne John , Schneider David , Liu Cunren , Lefkowitz Elliot , Crowley Michael , Georgiou George , Brown Elizabeth , Schroeder, Jr. Harry 
Published: January 2023

Abstract
Depressed serum immunoglobulin levels (sIgs) and recurrent sinopulmonary infections mark Common Variable Immune Deficiency (CVID). Many family members of CVID patients also suffer recurrent sinopulmonary infection (RESPI) but have normal sIg. We identified HLAB44 positive identical female twins who suffer sinopulmonary infections and are discordant for CVID and RESPI. Flow cytometry subsets showed equivalent numbers of immature B cells (BC) in both twins, but lower numbers of transitional and mature BC in the CVID twin. Deep sequencing of the immunoglobulin (Ig) repertoires expressed by the transitional and mature BC showed a significant divergence in the utilization of VH1 and VH4 family gene segments, with CVID favoring VH4 and RESPI VH1. RESPI twin used JH6 more frequently, whereas CVID twin used JH3. The amino acid composition of CDR-H3 repertoire was compared with a control; the twin and control tyrosine usage in transitional BC was similar (~15%) but greatly diverged in mature BC (control 15%, RESPI 25%, CVID &lt; 10%). Whole genome sequencing revealed homozygosity for a rare CD21 S639N polymorphism and heterozygosity for CD19 L174V. These findings suggest that in addition to an acquired block in BC development at the transitional stage, the CVID twin produces an Ig repertoire that is markedly depleted of tyrosine. This may explain why the function of the Ig repertoire in CVID is more impaired than what might be expected by sIgs levels.
Regulation of CD19 surface expression in human B cells by CD81 (P3323)
Authors: Levy Shoshana , Kuo Chiung-Chi , Sagi Yael , Chen Homer , Kela-Madar Neta , van Zelm Menno , van Dongen Jacques 
Published: January 2023

Abstract
A girl was diagnosed with primary antibody deficiency. Her B cells lacked surface CD19, although both alleles were normal. The cause was a homozygous exon splice site mutation in CD81(1). This human deficiency differs from CD81 knockout mice, in which surface CD19 is lower but not completely absent. The patient’s EBV-transformed B cells were used to determine how CD81 controls the trafficking of CD19. We show that the CD81 mutant (CD81mut) protein is expressed intracellularly in the patient’s B cells. Using a proximity ligation assay we also demonstrate that the truncated CD81mut protein interacts intracellularly with CD19. This interaction with the CD81mut protein abrogates carbohydrate maturation and trafficking of CD19 to the cell surface. However, expression of CD81mut did not exert a dominant negative effect on CD19 surface expression in B cells that express or lack CD81. Finally, using a reconstitution system we identify specific CD81 domains that restore carbohydrate maturation and cell surface expression of CD19 in the patient’s B cells. This specific case of antibody deficiency was manifested because of lack of surface expression of CD19, an important B cell signaling molecule. However, the maturation of CD19 and its trafficking to the cell surface require the presence of specific domains of the tetraspanin CD81 molecule. 1.van Zelm et al (2010) CD81 human gene defect disrupts CD19 complex formation and leads to antibody deficiency. J Clin Invest. 120: 1265.