Defining the correlates of lymphopenia and independent predictors of poor clinical outcome in adults hospitalized with COVID-19 in Australia

Lymphopenia is a common feature of acute COVID-19 and is associated with increased disease severity and 30-day mortality. Here we aim to define the demographic and clinical characteristics that correlate with lymphopenia in COVID-19 and determine if lymphopenia is an independent predictor of poor clinical outcome. We analysed the ENTER-COVID (Epidemiology of hospitalized in-patient admissions following planned introduction of Epidemic SARS-CoV-2 to highly vaccinated COVID-19 naïve population) dataset of adults (N = 811) admitted for COVID-19 treatment in South Australia in a retrospective registry study, categorizing them as (a) lymphopenic (lymphocyte count < 1 × 109/L) or (b) non-lymphopenic at hospital admission. Comorbidities and laboratory parameters were compared between groups. Multiple regression analysis was performed using a linear or logistic model. Intensive care unit (ICU) patients and non-survivors exhibited lower median lymphocyte counts than non-ICU patients and survivors respectively. Univariate analysis revealed that low lymphocyte counts associated with hypertension and correlated with haemoglobin, platelet count and negatively correlated with urea, creatinine, bilirubin, and aspartate aminotransferase (AST). Multivariate analysis identified age, male, haemoglobin, platelet count, diabetes, creatinine, bilirubin, alanine transaminase, c-reactive protein (CRP) and lactate dehydrogenase (LDH) as independent predictors of poor clinical outcome in COVID-19, while lymphopenia did not emerge as a significant predictor.

Clinical and laboratory features of COVID-19 illness and outcomes in immunocompromised individuals during the first pandemic wave in Sydney, Australia

People with immunocompromising conditions are at increased risk of SARS-CoV-2 infection and mortality, however early in the pandemic it was challenging to collate data on this heterogenous population. We conducted a registry study of immunocompromised individuals with polymerase chain reaction (PCR)-confirmed SARS-CoV-2 infection from March-October 2020 in Sydney, Australia to understand clinical and laboratory outcomes in this population prior to the emergence of the Delta variant. 27 participants were enrolled into the study including people with a haematologic oncologic conditions (n = 12), secondary immunosuppression (N = 8) and those with primary or acquired immunodeficiency (i.e. HIV; N = 7). All participants had symptomatic COVID-19 with the most common features being cough (64%), fever (52%) and headache (40%). Five patients demonstrated delayed SARS-CoV-2 clearance lasting three weeks to three months. The mortality rate in this study was 7% compared to 1.3% in the state of New South Wales Australia during the same period. This study provides data from the first eight months of the pandemic on COVID-19 outcomes in at-risk patient groups.

Measurable Residual Disease (MRD) by Flow Cytometry in Adult B-Acute Lymphoblastic Leukaemia (B-ALL) and Acute Myeloid Leukaemia (AML): Correlation with Molecular MRD Testing and Clinical Outcome at One Year

Measurable residual disease (MRD) detected by flow cytometry (FC) is well established in paediatric B- lymphoblastic leukaemia (B-ALL) and adult chronic lymphocytic leukaemia (CLL), but its utility in adult B-ALL and adult acute myeloid leukaemia (AML) is less clear. In this prospective MRD study, one of the largest in Australia to date, we examined consecutive bone marrow aspirates from adult participants with B-ALL (n = 47) and AML (n = 87) sent for FC-MRD testing at a quaternary referral hospital in Sydney. FC-MRD results were correlated to corresponding Mol-MRD testing where available and clinical outcomes at three-month intervals over 1 year. B-ALL showed a moderate positive correlation (rs = 0.401, p < 0.001), while there was no correlation between FC-MRD and Mol-MRD for AML (rs = 0.13, p = 0.237). Five FC-MRD patterns were identified which had significant associations with relapse (X2(4) = 31.17(4), p > 0.001) and survival (X2(4) = 13.67, p = 0.008) in AML, but not in B-ALL. The three-month MRD results were also strongly associated with survival in AML, while the association in B-ALL was less evident. There was a moderate correlation between FC-MRD and Mol-MRD in B-ALL but not AML. The association of FC-MRD with relapse and survival was stronger in AML than in B-ALL. Overall, these findings suggest divergent utilities of FC-MRD in AML and B-ALL.

Immune response to COVID-19 vaccination in patients with Waldenström macroglobulinaemia who pause their BTKi therapy

Patients with Waldenström macroglobulinaemia (WM) are at increased risk of severe COVID-19 infection and have poor immune responses to COVID-19 vaccination. This study assessed whether a closely monitored pause in Bruton's Tyrosine Kinase inhibitor (BTKi) therapy might result in an improved humoral response to a 3rd COVID-19 vaccine dose. Improved response was observed in WM patients who paused their BTKi, compared to a group who did not pause their BTKi. However, the response was attenuated after BTKi recommencement. This data contributes to our understanding of vaccination strategies in this patient group and may help inform consensus approaches in the future.

Risk Factors and Characteristics of Checkpoint Inhibitor-Associated Autoimmune Diabetes Mellitus (CIADM): A Systematic Review and Delineation From Type 1 Diabetes

BACKGROUND

Checkpoint inhibitor-associated autoimmune diabetes mellitus (CIADM) is a distinct form of autoimmune diabetes that is a rare complication of immune checkpoint inhibitor therapy. Data regarding CIADM are limited.

PURPOSE

To systematically review available evidence to identify presentation characteristics and risk factors for early or severe presentations of adult patients with CIADM.

DATA SOURCES

MEDLINE and PubMed databases were reviewed.

STUDY SELECTION

English full text articles from 2014 to April 2022 were identified with a predefined search strategy. Patients meeting diagnostic criteria for CIADM with evidence of hyperglycemia (blood glucose level >11 mmol/L or HbA1c ≥6.5%) and insulin deficiency (C-peptide <0.4 nmol/L and/or diabetic ketoacidosis [DKA]) were included for analysis.

DATA EXTRACTION

With the search strategy we identified 1,206 articles. From 146 articles, 278 patients were labeled with "CIADM," with 192 patients meeting our diagnostic criteria and included in analysis.

DATA SYNTHESIS

Mean ± SD age was 63.4 ± 12.4 years. All but one patient (99.5%) had prior exposure to either anti-PD1 or anti-PD-L1 therapy. Of the 91 patients tested (47.3%), 59.3% had susceptibility haplotypes for type 1 diabetes (T1D). Median time to CIADM onset was 12 weeks (interquartile range 6-24). DKA occurred in 69.7%, and initial C-peptide was low in 91.6%. T1D autoantibodies were present in 40.4% (73 of 179) and were significantly associated with DKA (P = 0.0009) and earlier time to CIADM onset (P = 0.02).

LIMITATIONS

Reporting of follow-up data, lipase, and HLA haplotyping was limited.

CONCLUSIONS

CIADM commonly presents in DKA. While T1D autoantibodies are only positive in 40.4%, they associate with earlier, more severe presentations.

Mortality and costs related to severe acute pancreatitis in the intensive care units of Australia and New Zealand (ANZ), 2003-2020

BACKGROUND AND OBJECTIVE

Comprehensive data on the burden of severe acute pancreatitis (SAP) in global intensive care units (ICUs) and trends over time are lacking. Our objective was to compare trends in hospital and ICU mortality, in-hospital and ICU length of stay, and costs related to ICU admission in Australia and New Zealand (ANZ) for SAP.

METHODS

We performed a retrospective, observational, cohort study of ICU admissions reported to the ANZ Intensive Care Society Adult Patient Database over three consecutive six-year time periods from 2003 to 2020.

RESULTS

12,635 patients with SAP from 189 ICUs in ANZ were analysed. No difference in adjusted hospital mortality (11.4% vs 11.5% vs 11.0%, p = 0.85) and ICU mortality rates (7.5% vs 8.0% vs 8.1%, p = 0.73) were noted over the study period. Median length of hospital admission reduced over time (13.9 days in 2003-08, 13.1 days in 2009-14 and 12.5 days in 2015-20; p < 0.01). No difference in length of ICU stay was noted over the study period (p = 0.13). The cost of managing SAP in ANZ ICUs remained constant over the three time periods.

CONCLUSIONS

In critically-ill SAP patients in ANZ, no change in mortality has been noted over nearly two decades. There was a slight reduction in hospital stay (1 day), while the length of ICU stay remained unchanged. Given the significant costs related to care of patients with SAP in ICU, these findings highlight the need to prioritise resource allocation for healthcare delivery and targeted clinical research to identify treatments aimed at reducing mortality.

Predicting vaccine effectiveness against severe COVID-19 over time and against variants: a meta-analysis

Vaccine protection from symptomatic SARS-CoV-2 infection has been shown to be strongly correlated with neutralising antibody titres; however, this has not yet been demonstrated for severe COVID-19. To explore whether this relationship also holds for severe COVID-19, we performed a systematic search for studies reporting on protection against different SARS-CoV-2 clinical endpoints and extracted data from 15 studies. Since matched neutralising antibody titres were not available, we used the vaccine regimen, time since vaccination and variant of concern to predict corresponding neutralising antibody titres. We then compared the observed vaccine effectiveness reported in these studies to the protection predicted by a previously published model of the relationship between neutralising antibody titre and vaccine effectiveness against severe COVID-19. We find that predicted neutralising antibody titres are strongly correlated with observed vaccine effectiveness against symptomatic (Spearman [Formula: see text] = 0.95, p < 0.001) and severe (Spearman [Formula: see text] = 0.72, p < 0.001 for both) COVID-19 and that the loss of neutralising antibodies over time and to new variants are strongly predictive of observed vaccine protection against severe COVID-19.

Fire in the belly: A scoping review of the immunopathological mechanisms of acute pancreatitis

Introduction

Acute pancreatitis (AP) is characterised by an inflammatory response that in its most severe form can cause a systemic dysregulated immune response and progression to acute multi-organ dysfunction. The pathobiology of the disease is unclear and as a result no targeted, disease-modifying therapies exist. We performed a scoping review of data pertaining to the human immunology of AP to summarise the current field and to identify future research opportunities.

Methods

A scoping review of all clinical studies of AP immunology was performed across multiple databases. Studies were included if they were human studies of AP with an immunological outcome or intervention.

Results

205 studies met the inclusion criteria for the review. Severe AP is characterised by significant immune dysregulation compared to the milder form of the disease. Broadly, this immune dysfunction was categorised into: innate immune responses (including profound release of damage-associated molecular patterns and heightened activity of pattern recognition receptors), cytokine profile dysregulation (particularly IL-1, 6, 10 and TNF-α), lymphocyte abnormalities, paradoxical immunosuppression (including HLA-DR suppression and increased co-inhibitory molecule expression), and failure of the intestinal barrier function. Studies including interventions were also included. Several limitations in the existing literature have been identified; consolidation and consistency across studies is required if progress is to be made in our understanding of this disease.

Conclusions

AP, particularly the more severe spectrum of the disease, is characterised by a multifaceted immune response that drives tissue injury and contributes to the associated morbidity and mortality. Significant work is required to develop our understanding of the immunopathology of this disease if disease-modifying therapies are to be established.

Human papillomavirus in the setting of immunodeficiency: Pathogenesis and the emergence of next-generation therapies to reduce the high associated cancer risk

Human papillomavirus (HPV), a common sexually transmitted virus infecting mucosal or cutaneous stratified epithelia, is implicated in the rising of associated cancers worldwide. While HPV infection can be cleared by an adequate immune response, immunocompromised individuals can develop persistent, treatment-refractory, and progressive disease. Primary immunodeficiencies (PIDs) associated with HPV-related disease include inborn errors of GATA, EVER1/2, and CXCR4 mutations, resulting in defective cellular function. People living with secondary immunodeficiency (e.g. solid-organ transplants recipients of immunosuppression) and acquired immunodeficiency (e.g. concurrent human immunodeficiency virus (HIV) infection) are also at significant risk of HPV-related disease. Immunocompromised people are highly susceptible to the development of cutaneous and mucosal warts, and cervical, anogenital and oropharyngeal carcinomas. The specific mechanisms underlying high-risk HPV-driven cancer development in immunocompromised hosts are not well understood. Current treatments for HPV-related cancers include surgery with adjuvant chemotherapy and/or radiotherapy, with clinical trials underway to investigate the use of anti-PD-1 therapy. In the setting of HIV co-infection, persistent high-grade anal intraepithelial neoplasia can occur despite suppressive antiretroviral therapy, resulting in an ongoing risk for transformation to overt malignancy. Although therapeutic vaccines against HPV are under development, the efficacy of these in the setting of PID, secondary- or acquired- immunodeficiencies remains unclear. RNA-based therapeutic targeting of the HPV genome or mRNA transcript has become a promising next-generation therapeutic avenue. In this review, we summarise the current understanding of HPV pathogenesis, immune evasion, and malignant transformation, with a focus on key PIDs, secondary immunodeficiencies, and HIV infection. Current management and vaccine regimes are outlined in relation to HPV-driven cancer, and specifically, the need for more effective therapeutic strategies for immunocompromised hosts. The recent advances in RNA-based gene targeting including CRISPR and short interfering RNA (siRNA), and the potential application to HPV infection are of great interest. An increased understanding of both the dysregulated immune responses in immunocompromised hosts and of viral persistence is essential for the design of next-generation therapies to eliminate HPV persistence and cancer development in the most at-risk populations.

High activation levels maintained in receptor-binding domain-specific memory B cells in people with severe coronavirus disease 2019

The long-term health consequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are still being understood. The molecular and phenotypic properties of SARS-CoV-2 antigen-specific T cells suggest a dysfunctional profile that persists in convalescence in those who were severely ill. By contrast, the antigen-specific memory B-cell (MBC) population has not yet been analyzed to the same degree, but phenotypic analysis suggests differences following recovery from mild or severe coronavirus disease 2019 (COVID-19). Here, we performed single-cell molecular analysis of the SARS-CoV-2 receptor-binding domain (RBD)-specific MBC population in three patients after severe COVID-19 and four patients after mild/moderate COVID-19. We analyzed the transcriptomic and B-cell receptor repertoire profiles at ~2 months and ~4 months after symptom onset. Transcriptomic analysis revealed a higher level of tumor necrosis factor-alpha (TNF-α) signaling via nuclear factor-kappa B in the severe group, involving CD80, FOS, CD83 and TNFAIP3 genes that was maintained over time. We demonstrated the presence of two distinct activated MBCs subsets based on expression of CD80^hi TNFAIP3^hi and CD11c^hi CD95^hi at the transcriptome level. Both groups revealed an increase in somatic hypermutation over time, indicating progressive evolution of humoral memory. This study revealed distinct molecular signatures of long-term RBD-specific MBCs in convalescence, indicating that the longevity of these cells may differ depending on acute COVID-19 severity.

Frontline workers: Mediators of mucosal immunity in community acquired pneumonia and COVID-19

The current COVID-19 pandemic has highlighted a need to further understand lung mucosal immunity to reduce the burden of community acquired pneumonia, including that caused by the SARS-CoV-2 virus. Local mucosal immunity provides the first line of defence against respiratory pathogens, however very little is known about the mechanisms involved, with a majority of literature on respiratory infections based on the examination of peripheral blood. The mortality for severe community acquired pneumonia has been rising annually, even prior to the current pandemic, highlighting a significant need to increase knowledge, understanding and research in this field. In this review we profile key mediators of lung mucosal immunity, the dysfunction that occurs in the diseased lung microenvironment including the imbalance of inflammatory mediators and dysbiosis of the local microbiome. A greater understanding of lung tissue-based immunity may lead to improved diagnostic and prognostic procedures and novel treatment strategies aimed at reducing the disease burden of community acquired pneumonia, avoiding the systemic manifestations of infection and excess morbidity and mortality.

Patients with treated indolent lymphomas immunized with BNT162b2 have reduced anti-spike neutralizing IgG to SARS-CoV-2 variants, but preserved antigen-specific T cell responses

Patients with indolent lymphoma undertaking recurrent or continuous B cell suppression are at risk of severe COVID-19. Patients and healthy controls (HC; N = 13) received two doses of BNT162b2: follicular lymphoma (FL; N = 35) who were treatment naïve (TN; N = 11) or received immunochemotherapy (ICT; N = 23) and Waldenström's macroglobulinemia (WM; N = 37) including TN (N = 9), ICT (N = 14), or treated with Bruton's tyrosine kinase inhibitors (BTKi; N = 12). Anti-spike immunoglobulin G (IgG) was determined by a high-sensitivity flow-cytometric assay, in addition to live-virus neutralization. Antigen-specific T cells were identified by coexpression of CD69/CD137 and CD25/CD134 on T cells. A subgroup (N = 29) were assessed for third mRNA vaccine response, including omicron neutralization. One month after second BNT162b2, median anti-spike IgG mean fluorescence intensity (MFI) in FL ICT patients (9977) was 25-fold lower than TN (245 898) and HC (228 255, p = .0002 for both). Anti-spike IgG correlated with lymphocyte count (r = .63; p = .002), and time from treatment (r = .56; p = .007), on univariate analysis, but only with lymphocyte count on multivariate analysis (p = .03). In the WM cohort, median anti-spike IgG MFI in BTKi patients (39 039) was reduced compared to TN (220 645, p = .0008) and HC (p < .0001). Anti-spike IgG correlated with neutralization of the delta variant (r = .62, p < .0001). Median neutralization titer for WM BTKi (0) was lower than HC (40, p < .0001) for early-clade and delta. All cohorts had functional T cell responses. Median anti-spike IgG decreased 4-fold from second to third dose (p = .004). Only 5 of 29 poor initial responders assessed after third vaccination demonstrated seroconversion and improvement in neutralization activity, including to the omicron variant.

Disentangling the relative importance of T cell responses in COVID-19: leading actors or supporting cast?

The rapid development of multiple vaccines providing strong protection from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been a major achievement. There is now compelling evidence for the role of neutralizing antibodies in protective immunity. T cells may play a role in resolution of primary SARS-CoV-2 infection, and there is a widely expressed view that T cell-mediated immunity also plays an important role in vaccine-mediated protection. Here we discuss the role of vaccine-induced T cells in two distinct stages of infection: firstly, in protection from acquisition of symptomatic SARS-CoV-2 infection following exposure; secondly, if infection does occur, the potential for T cells to reduce the risk of developing severe COVID-19. We describe several lines of evidence that argue against a direct impact of vaccine-induced memory T cells in preventing symptomatic SARS-CoV-2 infection. However, the contribution of T cell immunity in reducing the severity of infection, particularly in infection with SARS-CoV-2 variants, remains to be determined. A detailed understanding of the role of T cells in COVID-19 is critical for next-generation vaccine design and development. Here we discuss the challenges in determining a causal relationship between vaccine-induced T cell immunity and protection from COVID-19 and propose an approach to gather the necessary evidence to clarify any role for vaccine-induced T cell memory in protection from severe COVID-19.

Maintenance of broad neutralising antibodies and memory B cells 12 months post-infection is predicted by SARS-CoV-2 specific CD4+ T cell responses

Understanding the long-term maintenance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunity is critical for predicting protection against reinfection. In an age- and gender-matched cohort of 24 participants, the association of disease severity and early immune responses on the maintenance of humoral immunity 12 months post-infection is examined. All severely affected participants maintain a stable subset of SARS-CoV-2 receptor-binding domain (RBD)-specific memory B cells (MBCs) and good neutralizing antibody breadth against the majority of the variants of concern, including the Delta variant. Modeling these immune responses against vaccine efficacy data indicate a 45%–76% protection against symptomatic infection (variant dependent). Overall, these findings indicate durable humoral responses in most participants after infection, reasonable protection against reinfection, and implicate baseline antigen-specific CD4+ T cell responses as a predictor of maintenance of antibody neutralization breadth and RBD-specific MBC levels at 12 months post-infection.

Interferon-Gamma-Producing CD8+ Tissue Resident Memory T Cells Are a Targetable Hallmark of Immune Checkpoint Inhibitor-Colitis

BACKGROUND & AIMS

The pathogenesis of immune checkpoint inhibitor (ICI)-colitis remains incompletely understood. We sought to identify key cellular drivers of ICI-colitis and their similarities to idiopathic ulcerative colitis, and to determine potential novel therapeutic targets.

METHODS

We used a cross-sectional approach to study patients with ICI-colitis, those receiving ICI without the development of colitis, idiopathic ulcerative colitis, and healthy controls. A subset of patients with ICI-colitis were studied longitudinally. We applied a range of methods, including multiparameter and spectral flow cytometry, spectral immunofluorescence microscopy, targeted gene panels, and bulk and single-cell RNA sequencing.

RESULTS

We demonstrate CD8⁺ tissue resident memory T (T_RM) cells are the dominant activated T cell subset in ICI-colitis. The pattern of gastrointestinal immunopathology is distinct from ulcerative colitis at both the immune and epithelial-signaling levels. CD8⁺ T_RM cell activation correlates with clinical and endoscopic ICI-colitis severity. Single-cell RNA sequencing analysis confirms activated CD8⁺ T_RM cells express high levels of transcripts for checkpoint inhibitors and interferon-gamma in ICI-colitis. We demonstrate similar findings in both anti-CTLA-4/PD-1 combination therapy and in anti-PD-1 inhibitor-associated colitis. On the basis of our data, we successfully targeted this pathway in a patient with refractory ICI-colitis, using the JAK inhibitor tofacitinib.

CONCLUSIONS

Interferon gamma-producing CD8⁺ T_RM cells are a pathological hallmark of ICI-colitis and a novel target for therapy.

Identification of neutralising pembrolizumab anti-drug antibodies in patients with melanoma

Development of anti-drug antibodies (ADAs) can interfere with therapeutic monoclonal antibodies and may lead to drug neutralisation and clinical disease progression. Measurement of circulating drug levels and development of ADAs in the setting of anti-programmed cell death-1 agent pembrolizumab has not been well-studied. Enzyme-linked immunosorbent assays were used to measure pembrolizumab drug level and ADAs in 41 patients with melanoma at baseline, Time-point 1 (3 weeks) and Time-point 2 (21 weeks). Assay results were related to patient demographics and clinical outcome data at 6 months. The median pembrolizumab drug level at 3 weeks was 237 ng/μL and did not correlate with age, sex or body surface area.17/41 patients had an ADA detected at any timepoint, with the highest prevalence at Timepoint 1 (median concentration = 17 ng/μL). The presence of an ADA did not correlate with clinical progression at 6 months. 3/41 (7%) of patients displayed a falling pembrolizumab drug level and rising ADA titre between Timepoint 1 and 2 suggestive of a neutralising ADA. Pembrolizumab drug levels and ADAs can be readily measured. The rates of total and treatment-emergent ADAs may be higher in “real-word” settings than those previously reported. Larger studies are needed to determine effect of neutralising ADAs on long-term clinical outcome.

Decreased ATM Function Causes Delayed DNA Repair and Apoptosis in Common Variable Immunodeficiency Disorders

PURPOSE

Common variable immunodeficiency disorders (CVID) is characterized by low/absent serum immunoglobulins and susceptibility to bacterial infection. Patients can develop an infections-only phenotype or a complex disease course with inflammatory, autoimmune, and/or malignant complications. We hypothesized that deficient DNA repair mechanisms may be responsible for the antibody deficiency and susceptibility to inflammation and cancer in some patients.

METHODS

Germline variants were identified following targeted sequencing of n = 252 genes related to DNA repair in n = 38 patients. NanoString nCounter PlexSet assay measured gene expression in n = 20 CVID patients and n = 7 controls. DNA damage and apoptosis were assessed by flow cytometry in n = 34 CVID patients and n = 11 controls.

RESULTS

Targeted sequencing supported enrichment of rare genetic variants in genes related to DNA repair pathways with novel and rare likely pathogenic variants identified and an altered gene expression signature that distinguished patients from controls and complex patients from those with an infections-only phenotype. Consistent with this, flow cytometric analyses of lymphocytes following DNA damage revealed a subset of CVID patients whose immune cells have downregulated ATM, impairing the recruitment of other repair factors, delaying repair and promoting apoptosis.

CONCLUSION

These data suggest that germline genetics and altered gene expression predispose a subset of CVID patients to increased sensitivity to DNA damage and reduced DNA repair capacity.

Long-term persistence of RBD+ memory B cells encoding neutralizing antibodies in SARS-CoV-2 infection

Considerable concerns relating to the duration of protective immunity against severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) exist, with evidence of antibody titers declining rapidly after infection and reports of reinfection. Here, we monitor the antibody responses against SARS-CoV-2 receptor-binding domain (RBD) for up to 6 months after infection. While antibody titers are maintained, ∼13% of the cohort’s neutralizing responses return to background. However, encouragingly, in a selected subset of 13 participants, 12 have detectable RBD-specific memory B cells and these generally are increasing out to 6 months. Furthermore, we are able to generate monoclonal antibodies with SARS-CoV-2 neutralizing capacity from these memory B cells. Overall, our study suggests that the loss of neutralizing antibodies in plasma may be countered by the maintenance of neutralizing capacity in the memory B cell repertoire.

Decay of antibody binding to RBD and spike antigen after 6 months

11 of 81 (13.6%) participants revert to background neutralizing levels

Despite declining antibody titers, robust memory B cell populations are observed

Memory B cells retain potent neutralizing capacity

Unravelling Checkpoint Inhibitor Associated Autoimmune Diabetes: From Bench to Bedside

Immune checkpoint inhibitors have transformed the landscape of oncological therapy, but at the price of a new array of immune related adverse events. Among these is β-cell failure, leading to checkpoint inhibitor-related autoimmune diabetes (CIADM) which entails substantial long-term morbidity. As our understanding of this novel disease grows, parallels and differences between CIADM and classic type 1 diabetes (T1D) may provide insights into the development of diabetes and identify novel potential therapeutic strategies. In this review, we outline the knowledge across the disciplines of endocrinology, oncology and immunology regarding the pathogenesis of CIADM and identify possible management strategies.

Mucosal-associated invariant T (MAIT) cells are activated in the gastrointestinal tissue of patients with combination ipilimumab and nivolumab therapy-related colitis in a pathology distinct from ulcerative colitis

The aim of this study was to investigate the pathogenesis of combination ipilimumab and nivolumab-associated colitis (IN-COL) by measuring gut-derived and peripheral blood mononuclear cell (GMNC; PBMC) profiles. We studied GMNC and PBMC from patients with IN-COL, IN-treated with no adverse-events (IN-NAE), ulcerative colitis (UC) and healthy volunteers using flow cytometry. In the gastrointestinal-derived cells we found high levels of activated CD8⁺ T cells and mucosal-associated invariant T (MAIT) cells in IN-COL, changes that were not evident in IN-NAE or UC. UC, but not IN-C, was associated with a high proportion of regulatory T cells (T_reg ). We sought to determine if local tissue responses could be measured in peripheral blood. Peripherally, checkpoint inhibition instigated a rise in activated memory CD4⁺ and CD8⁺ T cells, regardless of colitis. Low circulating MAIT cells at baseline was associated with IN-COL patients compared with IN-NAE in one of two cohorts. UC, but not IN-COL, was associated with high levels of circulating plasmablasts. In summary, the alterations in T cell subsets measured in IN-COL-affected tissue, characterized by high levels of activated CD8⁺ T cells and MAIT cells and a low proportion of T_reg , reflected a pathology distinct from UC. These tissue changes differed from the periphery, where T cell activation was a widespread on-treatment effect, and circulating MAIT cell count was low but not reliably predictive of colitis.

Enhanced serum immunoglobulin G clearance in myotonic dystrophy-associated hypogammaglobulinemia: a case series and review of the literature

BACKGROUND

Myotonic dystrophy type 1 is an autosomal dominant disorder characterized by muscle weakness, myotonia, cataracts, and cardiac conduction defects; it is associated with expansions of cytosine-thymine-guanine repeats in the myotonic dystrophy protein kinase. Hypogammaglobulinemia is a lesser known association of myotonic dystrophy type 1 and the underlying pathogenesis of immunoglobulin G depletion remains unclear.

CASE PRESENTATION

Here we report a kindred of two members (a 62-year-old white woman and a 30-year-old white man; mother and son) with myotonic dystrophy type 1-associated hypogammaglobulinemia associated with altered intravenous immunoglobulin elimination kinetics and reduced half-life. There was no history of systemic immunosuppression or renal or gastrointestinal protein loss in either patient, and no underlying case for a secondary immunodeficiency could be found. One patient required fortnightly intravenous immunoglobulin to maintain adequate trough immunoglobulin G levels.

CONCLUSIONS

Ongoing study of myotonic dystrophy type 1-associated hypogammaglobulinemia using contemporary tools of genomic medicine may help to further delineate the pathogenesis of this entity.

Cerebral toxoplasmosis in a patient with myasthenia gravis and thymoma with immunodeficiency/Good's syndrome: a case report

Background

Patients with thymoma with immunodeficiency (TWI)/Good’s syndrome characteristically have evidence of combined immunodeficiency including low or absent B-cells, hypogammaglobulinemia and defects in T-cell mediated immunity. These patients can present with common or opportunistic infections.

Case presentation

A 54-year-old female was diagnosed with cerebral toxoplasmosis. This occurred on a background of metastatic thymoma previously treated with chemotherapy and myasthenia gravis (MG) treated with mycophenolate mofetil, monthly intravenous immunoglobulin (IVIG) and pyridostigmine. She reported recurrent herpes zoster infection. The patient had clinical and radiological progression of cerebral infection despite completing standard induction and maintenance therapy with sulfadiazine and pyrimethamine. Investigations found a complete absence of B-cells and evidence for hypogammaglobulinemia which, together with evidence of defects in T-cell mediated immunity and thymoma, lead to a diagnosis of TWI/Good’s Syndrome. The patient has undergone prolonged high-dose therapy for toxoplasmosis and a reduction in immunosuppression with no evidence of recurrent toxoplasmosis or flare of MG.

Conclusions

TWI/Good’s Syndrome should be suspected in patients with thymoma and recurrent, persistent or unusual infections. If suspected serum immunoglobulins and lymphocyte subsets should be measured. These patients may need closer monitoring, higher dose and prolonged treatment of infections, and weaning of concurrent immunosuppression may be considered.

Episodic fevers and vasodilatory shock mimicking urosepsis in a patient with HIV-associated multicentric Castleman's Disease: a case report

Background

Multicentric Castleman’s disease (MCD) is a pre-malignancy that presents with lymphadenopathy and features of systemic inflammation. Human immunodeficiency virus (HIV)-associated MCD is associated with human herpesvirus-8 (HHV-8) infection. If untreated MCD has a relapsing and remitting course that is eventually fatal.

Case presentation

A 67-year-old man had six hospital admissions over 20 months characterised by fever, urinary frequency and CRP >100 mg/L. The final admission was complicated by hypotension requiring intensive care unit admission and ionotropic support. His history included HIV and Hepatitis B virus (HBV) co-infection on suppressive therapy. Each presentation was managed as presumed urosepsis with use of empirical antibiotics, however numerous blood and urine cultures failed to identify a pathogen. A bone-marrow aspirate and trephine found no evidence of haematological malignancy. A positron emission tomography scan found active lymph nodes, one of which was biopsied and found to contain the plasma-cell variant of Castleman’s disease. Ultimately the cause for the recurrent presentations was attributed to progressive MCD. The patient received rituximab monotherapy and has had no further related admissions.

Conclusions

MCD should be considered in patients with chronic HIV infection presenting with recurrent sepsis-like episodes and/or vasodilatory shock, particularly if no pathogen is identified or lymphadenopathy is evident.

Posterior reversible encephalopathy syndrome (PRES) in an HIV-1 infected patient with disseminated varicella zoster virus: a case report

Background

Posterior reversible encephalopathy syndrome (PRES) is an uncommon pathology characterized by the acute onset of headache, vomiting, altered consciousness, seizures and focal neurological deficits. It was initially described in the setting of hypertension, uremia and immunosuppression. In the last decade there have been emerging reports of PRES in patients with advanced human immunodeficiency virus (HIV)-infection in the presence of hypertension, dialysis, hypercalcaemia and two opportunistic infections: blastomycosis and tuberculosis (TB).

Case presentation

Here we present the case of a 54 year old male being treated for disseminated varicella zoster virus (VZV) and vasculopathy in the setting of HIV infection who acutely deteriorated to the point of requiring intubation. His clinicoradiological diagnosis was of PRES and he subsequently improved within 72 h with supportive management. Serial neuroimaging correlated with the clinical findings. The pathogenesis of PRES is poorly understood but is thought to stem from vasogenic oedema either as a result of loss of endothelial integrity and transudate of fluid across the blood–brain barrier, or secondary to vasospasm resulting in tissue oedema in the absence of infarction. How HIV infection impacts on this model is unclear. It is possible the HIV infection causes endothelial dysfunction and disruption of the blood–brain barrier that may be further exacerbated by infections in the central nervous system.

Conclusion

The phenomenon of PRES in advanced HIV is an important clinical entity for both physicians and critical care doctors to recognize firstly given its potential mortality but also because of its favourable prognosis and reversibility with supportive care and treatment of underlying causes.

Progressive activation of CD127+132- recent thymic emigrants into terminally differentiated CD127-132+ T-cells in HIV-1 infection

Aim

HIV infection is associated with distortion of T-cell homeostasis and the IL-7/IL7R axis. Progressive infection results in loss of CD127+132− and gains in CD127−132+ CD4+ and CD8+ T-cells. We investigated the correlates of loss of CD127 from the T-cell surface to understand mechanisms underlying this homeostatic dysregulation.

Methods

Peripheral and cord blood mononuclear cells (PBMCs; CBMC) from healthy volunteers and PBMC from patients with HIV infection were studied. CD127+132−, CD127+132+ and CD127−132+ T-cells were phenotyped by activation, differentiation, proliferation and survival markers. Cellular HIV-DNA content and signal-joint T-cell receptor excision circles (sjTRECs) were measured.

Results

CD127+132− T-cells were enriched for naïve cells while CD127−132+ T-cells were enriched for activated/terminally differentiated T-cells in CD4+ and CD8+ subsets in health and HIV infection. HIV was associated with increased proportions of activated/terminally differentiated CD127−132+ T-cells. In contrast to CD127+132− T-cells, CD127−132+ T-cells were Ki-67+Bcl-2^low and contained increased levels of HIV-DNA. Naïve CD127+132− T-cells contained a higher proportion of sjTRECs.

Conclusion

The loss of CD127 from the T-cell surface in HIV infection is driven by activation of CD127+132− recent thymic emigrants into CD127−132+ activated/terminally differentiated cells. This process likely results in an irreversible loss of CD127 and permanent distortion of T-cell homeostasis.

The IL-7/IL-7 Receptor Axis: Understanding its Central Role in T-Cell Homeostasis and the Challenges Facing its Utilization as a Novel Therapy

Interleukin-7 (IL-7) is a cytokine produced predominantly by stromal cells of the thymus and bone marrow and is essential for lymphopoiesis. This paper reviews the importance of IL-7 and its receptor (IL-7R) in T-cell genesis, peripheral survival, expansion and memory T-cell development. IL-7 is of particular importance in lymphopenic conditions. Its expression is up-regulated in a number of lymphopenic conditions including: marrow ablation prior to bone marrow transplantation, marrow suppression following chemotherapy and human immuno-deficiency virus (HIV) infection. Plasma IL-7 levels inversely correlate with CD4+ T-cell counts in these conditions. Animal models suggest that IL-7 improves immune reconstitution through increasing thymic output and, perhaps more importantly, through antigen-independent homeostatic driven proliferation in the periphery. Given the promising preliminary data on the use of IL-7 adjuvant therapy in simian immuno-deficiency virus (SIV) infected non-human primates, IL-7 has recently moved into Phase I/II clinical trials of its role as a possible adjuvant therapy for cancer and HIV infection. This paper discusses important considerations such as the possible negative impacts of IL-7 on increased viral infectivity, the induction of autoimmunity and risk of neoplastic events. Successful use of IL-7 will rely on further understanding of the regulation of the component parts of the IL-7R system. Ultimately this understanding may lead to therapeutics that manipulate and optimise signalling through the IL-7/IL-7R system.

Infection of CD127+ (interleukin-7 receptor+) CD4+ cells and overexpression of CTLA-4 are linked to loss of antigen-specific CD4 T cells during primary human immunodeficiency virus type 1 infection

We recently found that human immunodeficiency virus (HIV)-specific CD4+ T cells express coreceptor CCR5 and activation antigen CD38 during early primary HIV-1 infection (PHI) but then rapidly disappear from the circulation. This cell loss may be due to susceptibility to infection with HIV-1 but could also be due to inappropriate apoptosis, an expansion of T regulatory cells, trafficking out of the circulation, or dysfunction. We purified CD38+++CD4+ T cells from peripheral blood mononuclear cells, measured their level of HIV-1 DNA by PCR, and found that about 10% of this population was infected. However, a small subset of HIV-specific CD4+) T cells also expressed CD127, a marker of long-term memory cells. Purified CD127+CD4+ lymphocytes contained fivefold more copies of HIV-1 DNA per cell than did CD127-negative CD4+ cells, suggesting preferential infection of long-term memory cells. We observed no apoptosis of antigen-specific CD4+ T cells in vitro and only a small increase in CD45RO+CD25+CD127dimCD4+ T regulatory cells during PHI. However, 40% of CCR5+CD38+++ CD4+ T cells expressed gut-homing integrins, suggesting trafficking through gut-associated lymphoid tissue (GALT). Furthermore, 80% of HIV-specific CD4+ T cells expressed high levels of the negative regulator CTLA-4 in response to antigen stimulation in vitro, which was probably contributing to their inability to produce interleukin-2 and proliferate. Taken together, the loss of HIV-specific CD4+ T cells is associated with a combination of an infection of CCR5+ CD127+ memory CD4+ T cells, possibly in GALT, and a high expression of the inhibitory receptor CTLA-4.

Increased plasma interleukin-7 level correlates with decreased CD127 and Increased CD132 extracellular expression on T cell subsets in patients with HIV-1 infection

BACKGROUND

Interleukin (IL)-7 levels are increased in patients with human immunodeficiency virus type 1 (HIV-1)-associated lymphopenia; however, the effects of this on IL-7 receptor (IL-7R) expression, disease progression, and immune reconstitution remain unclear.

METHODS

Plasma IL-7 levels were measured, by enzyme-linked immunoassay, in patients with primary, chronic, or long-term nonprogressive HIV-1 infection (PHI, CHI, and LTNP, respectively) before and after 40-48 weeks of antiretroviral therapy (ART). Cell-surface expression and intracellular expression of the IL-7R components CD127 and CD132 were measured by flow cytometry. The effects of IL-7 and cycloheximide on IL-7R expression by peripheral blood mononuclear cells were examined in vitro.

RESULTS

Plasma IL-7 levels were increased in both patients with PHI and those with CHI; administration of ART resulted in normalized plasma IL-7 levels in patients with PHI but not in those with CHI. Plasma IL-7 levels positively correlated with CD4(+) T cell immune reconstitution in patients with PHI. In vitro, exogenous IL-7 rapidly down-regulated cell-surface CD127 expression, but not CD132 expression, whereas subsequent reexpression required active protein synthesis. HIV-1 infection resulted in progressive decreases in the CD127(+)132(-) subset and increases in the CD127(-)132(+) subset of CD4(+) and CD8(+) T cells. Changes in CD4(+) T cell expression of IL-7R components were evident in patients with LTNP who lost viral control, and these changes preceded increases in plasma IL-7 levels.

CONCLUSIONS

Perturbations in the IL-7/IL-7R system were clearly associated with disease progression but did not reliably predict immune reconstitution.