Human T-follicular helper and T-follicular regulatory cell maintenance is independent of germinal centers.

The monoclonal anti-CD20 antibody rituximab (RTX) depletes B cells in the treatment of lymphoma and autoimmune disease, and contributes to alloantibody reduction in transplantation across immunologic barriers. The effects of RTX on T cells are less well described. T-follicular helper (Tfh) cells provide growth and differentiation signals to germinal center (GC) B cells to support antibody production, and suppressive T-follicular regulatory (Tfr) cells regulate this response. In mice, both Tfh and Tfr are absolutely dependent on B cells for their formation and on the GC for their maintenance. In this study, we demonstrate that RTX treatment results in a lack of GC B cells in human lymph nodes without affecting the Tfh or Tfr cell populations. These data demonstrate that human Tfh and Tfr do not require an ongoing GC response for their maintenance. The persistence of Tfh and Tfr following RTX treatment may permit rapid reconstitution of the pathological GC response once the B-cell pool begins to recover. Strategies for maintaining remission after RTX therapy will need to take this persistence of Tfh into account.

Performance of scoring systems in selecting short stay medical admissions suitable for assessment in same day emergency care: an analysis of diagnostic accuracy in a UK hospital setting.

OBJECTIVES: To assess the performance of the Amb score and Glasgow Admission Prediction Score (GAPS) in identifying acute medical admissions suitable for same day emergency care (SDEC) in a large urban secondary centre. DESIGN: Retrospective assessment of routinely collected data from electronic healthcare records. SETTING: Single large urban tertiary care centre. PARTICIPANTS: All unplanned admissions to general medicine on Monday-Friday, episodes starting 08:00-16:59 hours and lasting up to 48 hours, between 1 April 2019 and 9 March 2020. MAIN OUTCOME MEASURES: Sensitivity, specificity, positive and negative predictive value of the Amb score and GAPS in identifying patients discharged within 12 hours of arrival. RESULTS: 7365 episodes were assessed. 94.6% of episodes had an Amb score suggesting suitability for SDEC. The positive predictive value of the Amb score in identifying those discharged within 12 hours was 54.5% (95% CI 53.3% to 55.8%). The area under the receiver operating characteristic curve (AUROC) for the Amb score was 0.612 (95% CI 0.599 to 0.625).42.4% of episodes had a GAPS suggesting suitability for SDEC. The positive predictive value of the GAPS in identifying those discharged within 12 hours was 50.5% (95% CI 48.4% to 52.7%). The AUROC for the GAPS was 0.606 (95% CI 0.590 to 0.622).41.4% of the population had both an Amb and GAPS score suggestive of suitability for SDEC and 5.7% of the population had both and Amb and GAPS score suggestive of a lack of suitability for SDEC. CONCLUSIONS: The Amb score and GAPS had poor discriminatory ability to identify acute medical admissions suitable for discharge within 12 hours, limiting their utility in selecting patients for assessment within SDEC services within this diverse patient population.

Alemtuzumab for refractory primary systemic vasculitis-a randomised controlled dose ranging clinical trial of efficacy and safety (ALEVIATE).

BACKGROUND: Primary systemic vasculitis (PSV) is a heterogeneous group of autoimmune conditions. There is an unmet need for alternative therapies that lead to sustained remission in patients with refractory disease. Alemtuzumab, an anti-CD52 antibody, depletes lymphocytes for prolonged periods and, in retrospective studies, has induced sustained, treatment-free remissions in patients with refractory/relapsing vasculitis but has raised safety concerns of infection and secondary autoimmunity. This phase IIb clinical trial aimed to assess the efficacy and safety of alemtuzumab, at two different doses, in inducing remission in refractory vasculitis patients. METHODS: The ALEVIATE trial was a randomised, prospective, open-label, dose ranging clinical trial. Patients with refractory ANCA-associated vasculitis (AAV) or Behçet's disease (BD) were randomised to receive either 60 mg or 30 mg alemtuzumab. Treatments were administered at baseline and 6 months or earlier where clinically appropriate. A maximum of three treatments were allowed within the 12-month study period. RESULTS: Twenty-three patients received at least one dose of alemtuzumab. Twelve had AAV, and 11 a diagnosis of BD. The median age was 40 years (range 28-44), with a prior disease duration of 61 months (42-103). Sixteen (70%) achieved either complete (6/23, 26%) or partial (10/23, 44%) response at 6 months. Eight (35%) maintained remission to the end of the trial without relapse. Ten severe adverse events were observed in 7 (30%) patients; 4 were related to alemtuzumab. There were no differences in clinical endpoints between the 60 and 30 mg alemtuzumab treatment groups. CONCLUSION: In a selected group of refractory vasculitis patients, alemtuzumab led to remission in two thirds of patients at 6 months. Remission was maintained to 12 months in a third of the patients, and the safety profile was acceptable. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT01405807, EudraCT Number: 2009-017087-17. Registered on April 07, 2011.

A Complicated Pregnancy in an Adult with HNF4A p.R63W-Associated Fanconi Syndrome.

Renal Fanconi syndrome (RFS) is characterised by generalised dysfunction of the proximal renal tubules, resulting in excessive urinary loss of solutes, most notably bicarbonate, and type II (proximal) renal tubular acidosis. It is a rare condition, and literature around its management through pregnancy is limited. We present the management of a 37-year-old woman with RFS secondary to the HNF4A p.R63W mutation, through her third pregnancy. She presented at 28 + 5 weeks with dehydration, low serum bicarbonate, and profound metabolic acidosis. Daily infusions of sodium bicarbonate were necessary, and the requirements increased throughout the pregnancy. She also demonstrated both fasting hypoglycaemia and episodes of postprandial hyperglycaemia which required complex management. Due to concerns around fetal health, an elective caesarean section was performed at 34 weeks, delivering a healthy baby girl. This case highlights the potential complexity of pregnancy in patients with RFS and the need for a multidisciplinary approach to its management.

The adjuvant GLA-SE promotes human Tfh cell expansion and emergence of public TCRß clonotypes.

The generation of protective humoral immunity after vaccination relies on the productive interaction between antigen-specific B cells and T follicular helper (Tfh) cells. Despite the central role of Tfh cells in vaccine responses, there is currently no validated way to enhance their differentiation in humans. From paired human lymph node and blood samples, we identify a population of circulating Tfh cells that are transcriptionally and clonally similar to germinal center Tfh cells. In a clinical trial of vaccine formulations, circulating Tfh cells were expanded in Tanzanian volunteers when an experimental malaria vaccine was adjuvanted in GLA-SE but not when formulated in Alum. The GLA-SE-formulated peptide was associated with an increase in the extrafollicular antibody response, long-lived antibody production, and the emergence of public TCRß clonotypes in circulating Tfh cells. We demonstrate that altering vaccine adjuvants is a rational approach for enhancing Tfh cells in humans, thereby supporting the long-lived humoral immunity that is required for effective vaccines.

T Follicular Regulatory Cells and Antibody Responses in Transplantation.

De novo donor-specific antibody (DSA) formation is a major problem in transplantation, and associated with long-term graft decline and loss as well as sensitization, limiting future transplant options. Forming high-affinity, long-lived antibody responses involves a process called the germinal center (GC) reaction, and requires interaction between several cell types, including GC B cells, T follicular helper (Tfh) and T follicular regulatory (Tfr) cells. T follicular regulatory cells are an essential component of the GC reaction, limiting its size and reducing nonspecific or self-reactive responses.An imbalance between helper function and regulatory function can lead to excessive antibody production. High proportions of Tfh cells have been associated with DSA formation in transplantation; therefore, Tfr cells are likely to play an important role in limiting DSA production. Understanding the signals that govern Tfr cell development and the balance between helper and regulatory function within the GC is key to understanding how these cells might be manipulated to reduce the risk of DSA development.This review discusses the development and function of Tfr cells and their relevance to transplantation. In particular how current and future immunosuppressive strategies might allow us to skew the ratio between Tfr and Tfh cells to increase or decrease the risk of de novo DSA formation.

The Calcineurin Inhibitor Tacrolimus Specifically Suppresses Human T Follicular Helper Cells.

Background: T follicular helper (Tfh) cells are key players in the production of antibody-producing B cells via the germinal center reaction. Therapeutic strategies targeting Tfh cells are important where antibody formation is implicated in disease, such as transplant rejection and autoimmune diseases. We investigated the impact of the immunosuppressive agent tacrolimus on human Tfh cell differentiation and function in transplant recipients. Methods: Paired blood and lymph node (LN) samples were obtained from 61 transplant recipients immediately prior to organ implantation. Living-donor recipients received a week of tacrolimus prior to kidney transplantation. Deceased-donor recipients served as controls, as tacrolimus was not administered until after the transplant operation. Flow cytometry was used to compare LN and circulating cell subsets. Results: The calcineurin inhibitor (CNIs) tacrolimus specifically suppresses both LN Tfh cells and circulating Tfh cells, but not their regulatory counterparts or other CD4 T cell subsets. Conclusion: Our findings suggest that CNIs may have a more important role in the prevention of antibody formation than previously understood and, therefore, have potential for antibody-associated conditions in which aberrant Tfh function has been implicated in disease.

Superficial temporal recipient vessels in microvascular orbit and scalp reconstruction of oncologic defects.

The superficial temporal artery and vein (STA/V) are often considered suboptimal recipient vessels due to anecdotal reports that they are unreliable and prone to spasm. This is unfortunate, as their position greatly facilitates reconstruction of the scalp and orbit. We present our experience with 28 patients who underwent microvascular craniofacial reconstruction of oncological defects using the STA/V as recipients over a 4-year period at a single institution. Rates of vessel thrombosis, total flap loss, and partial flap loss were not significantly different from 282 flaps anastomosed to neck vessels. With knowledge of the anatomy and proper technique, the STA/V are reliable and available in most patients and can facilitate microvascular orbit and scalp reconstruction. The proximity they offer allows more flexibility in flap pedicle length requirement and avoids the use of vein grafts. Caution should be exercised if there is a history of radiation therapy.