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The effects of added salt, proteins, and phosphates on the characteristics of fillets are evaluated. The composition of brine varied with groups, containing phosphates, salts, proteins or hydrolyzed cod proteins are discussed.

The complement receptor 2 (CR2, CD21) is part of a complex (CD21/CD19/CD81) acting as a co-receptor to the B cell receptor (BCR). Simultaneous triggering of the BCR and CD21 lowers the threshold for B cell activation. Although CD21 is important, B cells that express low amounts or lack surface CD21 (CD21-/low) are increased in conditions with chronic inflammation, e.g. autoimmune diseases. However, little is known about the CD21-/low B cell subset in peripheral blood from healthy donors. Here, we show that CD21-/low cells represent approximately 5% of B cells in peripheral blood from adults but are barely detectable in cord blood, after excluding transitional B cells. The CD21-/low subset can be divided into CD38-24+ and CD38-24low cells, where most of the CD38-24+ are CD27+immunoglobulin (Ig)M+IgD+ and the CD38-24low are switched CD27-. Expression levels of additional markers, e.g. CD95 and CD62L, are similar to those on classical memory B cells. In contrast to naive cells, the majority of CD21-/low cells lack expression of the ABCB1 transporter. Stimulation with a combination of BCR, Toll-like receptor (TLR)−7/8 and interleukin (IL)−2 induces proliferation and differentiation of the CD21-/low B cells comparable to CD21+CD27+ memory B cells. The response excluding BCR agonist is not on par with that of classical memory B cells, although clearly above that of naive B cells. This is ascribed to a weaker response by the CD38-24low subset, implying that some memory B cells require not only TLR but also BCR triggering. We conclude that the CD21-/low cells in healthy donors are memory B cells. [ABSTRACT FROM AUTHOR]

B cells represent one of the cellular components of the immune system that protects the individual from invading pathogens. In response to the invader, these cells differentiate into plasma cells and produce large amounts of antibodies that bind to and eliminate the pathogen. A hallmark of autoimmune diseases is the production of autoantibodies i.e. antibodies that recognize self. Those that are considered pathogenic can damage tissues and organs, either by direct binding or when deposited as immune complexes. For decades, B cells have been considered to play a major role in autoimmune diseases by antibody production. However, as pathogenic autoantibodies appear to derive mainly from T cell dependent responses, T cells have been the focus for many years. The successful treatment of patients with autoimmune diseases with either B cell depletion therapy (rituximab) or inhibition of B cell survival (belimumab), suggested that not only the autoantibodies but also other B cell features are important. This has caused a surge of interest in B cells and their biology resulting in the identification of various subsets e.g. regulatory B cells, several memory B cell subsets etc. Also, in other conditions such as chronic viral infections and primary immunodeficiency, several B cell subsets with unique characteristics have been identified. In this review, we will discuss one of these subsets, a subset that is expanded in conditions characterized by chronic immune stimulation. This B cell subset lacks, or expresses low, surface levels of the complement receptor 2 ( CD21) and has therefore been termed CD21−/low B cells. [ABSTRACT FROM AUTHOR]

This paper is an account of a project funded by the European Union as a Leonardo da Vinici pilot project which aimed to produce a framework for a programme which prepares qualified nurses for their role as mentor of the student nurse. Representatives from universities in Norway, Sweden, Iceland, Poland, Portugal and the United Kingdom were the partner countries. The project was developed through the establishment of a series of common meetings sequentially held in each of the partner countries. The aim of these meetings was to devise a common curriculum for the preparation of mentors of students, when in practice, thereby sharing views, experiences and expectations. Initially, the group established a common philosophy specifically theory and practice were seen as a single entity with theory being both related to and drawn from practice. Reflection and reflection on practice was also seen as important; an inductive model which emphasized the dialectical relationship between theory (abstract thinking), practice (concrete experiences), reflected observation (induction) and active experimentation (deduction) and serve to reduce the gap between theory and practice. The process evolved rather than was a predetermined plan but on reflection the process involved several stages: the first lay in the identification of a common understanding of terms and a shared common philosophy. A framework is then devised which allows the partner countries to develop their programme according to local and national needs. [ABSTRACT FROM AUTHOR]

Fillets of cod (Gadus morhua) were salted in a traditional way and with the addition of polyphosphates. After 3 weeks of storage, the fillets were rehydrated and desalted. Changes in weight and chemical content were followed through the process. The addition of polyphosphates resulted in poorer quality, when considering the entire process, although differences were not observed in sensory evaluation after rehydration and steam boiling. Improvements in yield were observed in the fillets containing polyphosphate, after dry-salting and storage (P < 0.05). However, the increase in weight during rehydration was far less by those fillets than by the control group, where no phosphate was used. [ABSTRACT FROM AUTHOR]

Objectives: Real-world evidence is needed to inform treatment strategies for patients with PsA and axial SpA (axSpA) who have non-musculoskeletal manifestations (NMMs), various risk factors and comorbidities. International collaboration is required to ensure statistical power and to enhance generalizability. The first step forward is identifying which data are currently being collected. Across 17 registries participating in the European Spondyloarthritis Research Collaboration (EuroSpA), we aimed to map recording practices for NMMs, comorbidities and safety outcomes in patients with PsA and axSpA., Methods: Through a survey with 4,420 questionnaire items, we explored the recording practices of 58 pre-defined conditions (i.e. NMMs, comorbidities and safety outcomes) covering 10 disease areas. In all registries we mapped for each condition whether it was recorded, the recording procedure and the potential to identify it through linkage to other national registries., Results: Conditions were generally recorded at entry into the registry and clinical follow-up visits using a pre-specified list or a coding system. Most registries recorded conditions within the following disease areas: NMMs (number of registries, n  = 15-16), cardiovascular diseases ( n  = 10-14), gastrointestinal diseases ( n  = 12-13), infections ( n  = 10-13) and death ( n  = 14). Nordic countries had the potential for data linkage and generally had limited recording of conditions in their registry, while other countries had comprehensive recording practices., Conclusion: A wide range of conditions were consistently recorded across the registries. The recording practices of many conditions and disease areas were comparable across the registries. Our findings support the potential for future collaborative research., (© The Author(s) 2024. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objective: Subsets of CD21 -/low memory B cells (MBCs), including double-negative (DN, CD27 - IgD - ) and Tbet + CD11c + cells, are expanded in chronic inflammatory diseases. In rheumatoid arthritis (RA), CD21 -/low MBCs correlate with joint destruction. However, whether this is due to the Tbet + CD11c + subset, its function and pathogenic contribution to RA are unknown. This study aims to investigate the association between CD21 -/low Tbet + CD11c + MBCs and joint destruction as well as other clinical parameters and to elucidate their functional properties in patients with untreated RA (uRA)., Methods: Clinical observations were combined with flow cytometry (n = 36) and single-cell RNA sequencing (scRNA-seq) and V(D)J sequencing (n = 4) of peripheral blood (PB) MBCs from patients with uRA. The transcriptome of circulating Tbet + CD11c + MBCs was compared with scRNA-seq data of synovial B cells. In vitro coculture of Tbet + CD11c + B cells with T cells was used to assess costimulatory capacity., Results: CD21 -/low Tbet + CD11c + MBCs in PB correlated with bone destruction but no other clinical parameters analyzed. The Tbet + CD11c + MBCs have undergone clonal expansion and express somatically mutated V genes. Gene expression analysis of these cells identified a unique signature of more than 150 up-regulated genes associated with antigen presentation functions, including B cell receptor activation and clathrin-mediated antigen internalization; regulation of actin filaments, endosomes, and lysosomes; antigen processing, loading, presentation, and costimulation; a transcriptome mirrored in their synovial tissue counterparts. In vitro, Tbet + CD11c + B cells induced retinoic acid receptor-related orphan nuclear receptor γT expression in CD4 + T cells, thereby polarizing to Th17 cells, a T cell subset critical for osteoclastogenesis and associated with bone destruction., Conclusion: This study suggests that Tbet + CD11c + MBCs contribute to the pathogenesis of RA by promoting bone destruction through antigen presentation, T cell activation, and Th17 polarization., (© 2024 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Background: There is emerging evidence that a brief cognitive task intervention may reduce the frequency of intrusive memories, even long-standing memories of older trauma. However, evaluations to date have involved in-person researcher contact. We investigated the feasibility and acceptability of remote delivery to women (n = 12) in Iceland who had experienced trauma on average two decades earlier., Method: Participants monitored intrusive memories in a daily diary for one week (i.e., baseline phase), completed (at least) two guided, remote intervention sessions (e.g., via secure video platform), and were encouraged to continue to use the intervention self-guided., Results: Eight participants completed the primary outcome and reported fewer intrusive memories in Week 5 (M = 6.98, SD = 5.73) compared to baseline (M = 25.98, SD = 29.39) - a 68% reduction. Intrusions decreased at each subsequent time point; at 3-months (n = 7) there was a 91% reduction compared to baseline. Other psychological symptoms reduced and functioning improved. Importantly, participant ratings and qualitative feedback support feasibility and acceptability., Conclusion: Findings suggest the feasibility of remote delivery of the brief imagery-competing task intervention by non-specialists (who were not mental health professionals) and hold promise for developing psychotherapeutic innovations supporting women with intrusive memories even decades after trauma., Competing Interests: EAH has written books on mental imagery with Guilford Press and Oxford University Press and receives occasional honoraria for conference keynotes and clinical workshops. EAH is on the Board of Trustees of the MQ Foundation. EAH has developed the intervention approach to reduce intrusive memories and training in using it (ANEMONE ™). EAH salary is part funded by the Wellcome Trust (223016/Z/21/Z) via consultancy to P1vital Products Ltd (a study not part of the current work).

Background: Involvement of B cells in the pathogenesis of rheumatoid arthritis (RA) is supported by the presence of disease-specific autoantibodies and the efficacy of treatment directed against B cells. B cells that express low levels of or lack the B cell receptor (BCR) co-receptor CD21, CD21 -/low B cells, have been linked to autoimmune diseases, including RA. In this study, we characterized the CD21 + and CD21 -/low B cell subsets in newly diagnosed, early RA (eRA) patients and investigated whether any of the B cell subsets were associated with autoantibody status, disease activity and/or joint destruction., Methods: Seventy-six eRA patients and 28 age- and sex-matched healthy donors were recruited. Multiple clinical parameters were assessed, including disease activity and radiographic joint destruction. B cell subsets were analysed in peripheral blood (PB) and synovial fluid (SF) using flow cytometry., Results: Compared to healthy donors, the eRA patients displayed an elevated frequency of naïve CD21 + B cells in PB. Amongst memory B cells, eRA patients had lower frequencies of the CD21 + CD27 + subsets and CD21 -/low CD27 + IgD + subset. The only B cell subset found to associate with clinical factors was the CD21 -/low double-negative (DN, CD27 - IgD - ) cell population, linked with the joint space narrowing score, i.e. cartilage destruction. Moreover, in SF from patients with established RA, the CD21 -/low DN B cells were expanded and these cells expressed receptor activator of the nuclear factor κB ligand (RANKL)., Conclusions: Cartilage destruction in eRA patients was associated with an expanded proportion of CD21 -/low DN B cells in PB. The subset was also expanded in SF from established RA patients and expressed RANKL. Taken together, our results suggest a role for CD21 -/low DN in RA pathogenesis., (© 2024. The Author(s).)

Cognitive theories of post-traumatic stress disorder (PTSD) feature appraisal of trauma as a critical factor in the development and maintenance of the disorder. Here we explored appraisals of social trauma (severe rejection or humiliation). Participants were outpatients with social anxiety disorder (SAD) and clinically significant PTSD symptoms (PTSS) after social trauma (n = 15); two clinical control groups of either SAD (n = 32) or obsessive-compulsive disorder (OCD; n = 13); and a control group with no diagnoses (n = 38). Measures included a clinical interview to assess social trauma and related open-ended appraisals and the Posttraumatic Cognitions Inventory (PTCI). Raters blind to group assignment performed content analyses of appraisals. Results showed that the PTSS group scored significantly higher than either clinical group on the PTCI SELF subscale. Only the SELF subscale predicted a diagnosis of both PTSS and SAD. All but one PTSS participant reported primarily negative beliefs about their social trauma, and the most common categories were flawed self and others are critical or cruel. Post-traumatic appraisals implicated in the course of PTSD are significant in how individuals respond to social trauma, with negative self-cognitions linked to both PTSS and SAD.

Memory B cells (MBCs) are an essential part of our immunological memory. They respond fast upon re-encountering pathogens and can differentiate into plasma cells that secrete protective antibodies. The focus of this review is on MBCs that lack, or express low levels of, CD21, hereafter referred to as CD21-/low. These cells are expanded in peripheral blood with age and during chronic inflammatory conditions such as viral infections, malaria, common variable immunodeficiency, and autoimmune diseases. CD21-/low MBCs have gained significant attention; they produce disease-specific antibodies/autoantibodies and associate with key disease manifestations in some conditions. These cells can be divided into subsets based on classical B-cell and other markers, e.g. CD11c, FcRL4, and Tbet which, over the years, have become hallmarks to identify these cells. This has resulted in different names including age-associated, autoimmune-associated, atypical, tissue-like, tissue-resident, tissue-restricted, exhausted, or simply CD21-/low B cells. It is however unclear whether the expanded 'CD21-/low' cells in one condition are equivalent to those in another, whether they express an identical gene signature and whether they have a similar function. Here, we will discuss these issues with the goal to understand whether the CD21-/low B cells are comparable in different conditions., (© The Author(s) 2022. Published by Oxford University Press on behalf of the British Society for Immunology.)

CD38 is a multifunctional protein expressed on the surface of B cells in healthy individuals but also in B cell malignancies. Previous studies have suggested a connection between CD38 and components of the IgM class B cell antigen receptor (IgM-BCR) and its coreceptor complex. Here, we provide evidence that CD38 is closely associated with CD19 in resting B cells and with the IgM-BCR upon engagement. We show that targeting CD38 with an antibody, or removing this molecule with CRISPR/Cas9, inhibits the association of CD19 with the IgM-BCR, impairing BCR signaling in normal and malignant B cells. Together, our data suggest that CD38 is a new member of the BCR coreceptor complex, where it exerts a modulatory effect on B cell activation upon antigen recognition by regulating CD19. Our study also reveals a new mechanism where α-CD38 antibodies could be a valuable option in therapeutic approaches to B cell malignancies driven by aberrant BCR signaling., (© 2022 Camponeschi et al.)

Background: Novel interventions should be developed for people who have undergone psychological trauma. In a previous case study, we found that the number of intrusive memories of trauma could be reduced with a novel intervention. The intervention included a brief memory reminder, a visuospatial task and mental rotation, and targeted trauma memory hotspots one at a time in separate sessions., Objective: This case series (N=3) extended the first case study with 3 new cases to determine whether a similar pattern of beneficial results is observed. We explored whether the brief intervention would result in reduced numbers of intrusive memories and whether it would impact symptoms of posttraumatic stress, depression and anxiety, and general functioning. Acceptability of the intervention was also explored., Methods: A total of 3 women completed the study: 2 with posttraumatic stress disorder and other comorbidities and 1 with subthreshold posttraumatic stress disorder. The primary outcome was the change in the number of intrusive memories from the baseline phase to the intervention phase and at the 1-month follow-up, with an assessment of the intrusion frequency at 3 months. Participants monitored the number of intrusive memories in a daily diary for 1 week at baseline, for maximum of 6 weeks during the intervention phase and for 1 week at the 1-month and 3-month follow-ups. The intervention was delivered in person or digitally, with guidance from a clinical psychologist. A repeated AB design was used (A was a preintervention baseline phase and B intervention phase). Intrusions were targeted individually, creating repetitions of an AB design., Results: The total number of intrusive memories was reduced from the baseline to the intervention phase for all participants. The total number for participant 3 (P3) reduced from 38.8 per week during the baseline phase to 18.0 per week in the intervention phase. It was 13 at the 3-month follow-up. The total number for P4 reduced from 10.8 per week at baseline to 4.7 per week in the intervention phase. It was 0 at the 3-month follow-up. The total number for P5 was reduced from 33.7 at baseline to 20.7 per week in the intervention phase. It was 8 at the 3-month follow-up. All participants reported reduction in posttraumatic stress symptoms in the postintervention phase. Depression and anxiety symptoms reduced in 2 of the 3 participants in the postintervention phase. Acceptability was favorable., Conclusions: We observed good compliance with the intervention and intrusive memory diary in all 3 cases. The number of intrusive memories was reduced for all participants during the intervention phase and at the 1-month follow-up, with some improvement in other symptoms and functioning. Further research should explore the remote delivery of the intervention and whether nonspecialists can deliver the intervention effectively., (©Kristjana Thorarinsdottir, Emily A Holmes, Johann Hardarson, Elin S Stephenssen, Marianna H Jonasdottir, Marie Kanstrup, Laura Singh, Arna Hauksdottir, Thorhildur Halldorsdottir, Berglind Gudmundsdottir, Edda Thordardottir, Unnur Valdimarsdottir, Andri Bjornsson. Originally published in JMIR Formative Research (https://formative.jmir.org), 20.07.2022.)

Background: Additional interventions are needed for survivors of psychological trauma because of several barriers to and limitations of existing treatment options (eg, need to talk about the trauma in detail). Case studies are an important step in exploring the development of novel interventions, allowing detailed examination of individual responses to treatment over time. Here, we present a case study that aims to test a novel intervention designed to disrupt memory reconsolidation, taking a single-symptom approach by focusing on intrusive memories of a traumatic event., Objective: This study aims to examine a novel brief cognitive intervention to reduce the number of intrusive memories of trauma in an Icelandic setting and to extend previous studies by examining long-term effects for up to 3 months. The intervention was guided by a clinical psychologist and comprised a brief memory reminder, followed by Tetris gameplay with mental rotation, targeting one memory at a time in each session., Methods: This was a single case study in Iceland with a woman in her 50s (drawn from an epidemiological study of trauma) with subthreshold posttraumatic stress disorder and a diagnosis of obsessive-compulsive disorder and social anxiety disorder. The participant had four different intrusive memories from a traumatic event that happened in her childhood. The primary outcome was the change in the number of intrusive memories from baseline to intervention phase and to follow-ups. The number of intrusions was monitored in a daily diary for 4 weeks preintervention, 8 weeks during the intervention, and 1 week at 1-month and 3-month follow-ups. Intrusions were targeted one by one over six intervention sessions, creating four repetitions of an AB design (ie, length of baseline A and intervention phase B varied for each memory). We examined changes in both the total number of intrusions (summed across all four memories) and individually for each memory. In addition, we explored whether having fewer intrusive memories would have an impact on functioning, posttraumatic stress, and depression or anxiety symptoms., Results: The total number of intrusions per week was 12.6 at baseline, 6.1 at the intervention phase (52% reduction from baseline), 3.0 at the 1-month follow-up (76% reduction), and 1.0 at the 3-month follow-up (92% reduction). Reductions in the symptoms of posttraumatic stress and depression were observed postintervention. Sleep, concentration, stress, and functioning improved. The participant considered the gameplay intervention acceptable and helpful in that she found that the memories disappeared while she was playing., Conclusions: This guided brief cognitive intervention reduced the number of intrusive memories over the intervention phase and follow-ups. The brief memory reminder was well tolerated, removing the need to discuss trauma in detail. The next steps require an extension to more cases and exploring remote delivery of the intervention., (©Kristjana Thorarinsdottir, Emily A Holmes, Johann Hardarson, Unnur Hedinsdottir, Marie Kanstrup, Laura Singh, Arna Hauksdottir, Thorhildur Halldorsdottir, Berglind Gudmundsdottir, Unnur Valdimarsdottir, Edda Bjork Thordardottir, Beau Gamble, Andri Bjornsson. Originally published in JMIR Formative Research (https://formative.jmir.org), 04.11.2021.)

The key characteristic of a traumatic event as defined by the Diagnostic and Mental Manual of Mental Disorders (DSM) seems to be a threat to life. However, evidence suggests that other types of threats may play a role in the development of PTSD and other disorders such as social anxiety disorder (SAD). One such threat is social trauma, which involves humiliation and rejection in social situations. In this study, we explored whether there were differences in the frequency, type and severity of social trauma endured by individuals with a primary diagnosis of SAD (n = 60) compared to a clinical control group of individuals with a primary diagnosis of obsessive compulsive disorder (OCD, n = 19) and a control group of individuals with no psychiatric disorders (n = 60). The results showed that most participants in this study had experienced social trauma. There were no clear differences in the types of experiences between the groups. However, one third of participants in the SAD group (but none in the other groups) met criteria for PTSD or suffered from clinically significant PTSD symptoms in response to their most significant social trauma. This group of SAD patients described more severe social trauma than other participants. This line of research could have implications for theoretical models of both PTSD and SAD, and for the treatment of individuals with SAD suffering from PTSD after social trauma., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Depletion of B cells is beneficial in rheumatoid arthritis (RA) patients with autoantibodies to citrullinated proteins (ACPA) and/or the Fc portion of immunoglobulins (rheumatoid factor [RF]), suggesting a role for B cells in disease pathogenesis. To date, however, the identity of specifically pathogenic B cell subsets has not been discovered. One candidate population is identified by the low expression or absence of complement receptor 2 (CD21 -/low B cells). In this study, we sought to determine whether there was any correlation between CD21 -/low B cells and clinical outcome in patients with established RA, either ACPA + /RF + (n = 27) or ACPA - /RF - (n = 10). Healthy donors (n = 17) were included as controls. The proportion of the CD21 -/low CD27 - IgD - memory B cell subset in peripheral blood (PB) was significantly increased in ACPA + /RF + RA patients compared with healthy donors, and the frequency of this subset correlated with joint destruction (r = 0.57, P < 0.04). The levels of the chemokines CXCL-9 and CXCL-10 were higher in synovial fluid than in plasma, and PB CD21 -/low cells expressed the receptor, CXCR3. In synovial fluid, most of the B cells were CD21 -/low , approximately 40% of that population was CD27 - IgD - , and a third of those expressed the pro-osteoclastogenic factor receptor activator of the nuclear factor κB ligand (RANKL). This subset also secreted RANKL, in addition to other factors such as IL-6, even in the absence of stimulation. We interpret these data as reason to propose the hypothesis that the CD27 - IgD - subset of CD21 -/low B cells may mediate joint destruction in patients with ACPA + /RF + RA., (© 2019 The Foundation for the Scandinavian Journal of Immunology.)

Immunological memory ensures life-long protection against previously encountered pathogens, and in mice and humans the spleen is an important reservoir for long-lived memory B cells (MBCs). It is well-established that integrins play several crucial roles in lymphocyte survival and trafficking, but their involvement in the retention of MBCs in secondary lymphoid organs, and differences between B cell subsets in their adhesion capacity to ICAM-1 and/or VCAM-1 have not yet been confirmed. Here, we use an autoimmune mouse model, where MBCs are abundant, to show that the highest levels of LFA-1 and VLA-4 amongst B cells are found on MBCs. In vivo blockade of VLA-4 alone or in combination with LFA-1, but not LFA-1 alone, causes a release of MBCs from the spleen into the blood stream. In humans, we find that in peripheral blood, spleens, and tonsils from healthy donors the highest expression levels of the integrins LFA-1 and VLA-4 are also found on MBCs. Consistent with this, we found MBCs to have a higher capacity to adhere to ICAM-1 and VCAM-1 than naïve B cells. In patients with the autoimmune disease rheumatoid arthritis, it is the MBCs that have the highest levels of LFA-1 and VLA-4; moreover, compared with healthy donors, naïve B and MBCs of patients receiving anti-TNF medication have enhanced levels of the active form of LFA-1. Commensurate levels of the active αL subunit can be induced on B cells from healthy donors by exposure to the integrin ligands. Thus, our findings establish the selective use of the integrins LFA-1 and VLA-4 in the localization and adhesion of MBCs in both mice and humans.

Background: The mechanisms underlying tolerance induction and maintenance in autoimmune arthritis remain elusive. In a mouse model of rheumatoid arthritis, collagen type II (CII)-induced arthritis, we explore the contribution of B cells to antigen-specific tolerance., Methods: To generate expression of the CII-peptide specifically on B-cell major histocompatibility complex type II, lentiviral-based gene therapy including a B-cell-specific Igk promoter was used., Results: Presentation of the CII-peptide on B cells significantly reduced the frequency and severity of arthritis as well as the serum levels of CII -specific IgG antibodies. Further, both frequency and suppressive function of regulatory T cells were increased in tolerized mice. Adoptive transfer of regulatory T cells from tolerized mice to naïve mice ameliorated the development of CII-induced arthritis., Conclusion: Our data suggest that endogenous presentation of the CII-peptide on B cells is one of the key contributors to arthritis tolerance induction and maintenance.

B cells represent one of the cellular components of the immune system that protects the individual from invading pathogens. In response to the invader, these cells differentiate into plasma cells and produce large amounts of antibodies that bind to and eliminate the pathogen. A hallmark of autoimmune diseases is the production of autoantibodies i.e. antibodies that recognize self. Those that are considered pathogenic can damage tissues and organs, either by direct binding or when deposited as immune complexes. For decades, B cells have been considered to play a major role in autoimmune diseases by antibody production. However, as pathogenic autoantibodies appear to derive mainly from T cell dependent responses, T cells have been the focus for many years. The successful treatment of patients with autoimmune diseases with either B cell depletion therapy (rituximab) or inhibition of B cell survival (belimumab), suggested that not only the autoantibodies but also other B cell features are important. This has caused a surge of interest in B cells and their biology resulting in the identification of various subsets e.g. regulatory B cells, several memory B cell subsets etc. Also, in other conditions such as chronic viral infections and primary immunodeficiency, several B cell subsets with unique characteristics have been identified. In this review, we will discuss one of these subsets, a subset that is expanded in conditions characterized by chronic immune stimulation. This B cell subset lacks, or expresses low, surface levels of the complement receptor 2 (CD21) and has therefore been termed CD21(-/low) B cells., (© 2015 The Foundation for the Scandinavian Journal of Immunology.)