COVID-19-neutralizing antibodies predict disease severity and survival.

Coronavirus disease 2019 (COVID-19) exhibits variable symptom severity ranging from asymptomatic to life-threatening, yet the relationship between severity and the humoral immune response is poorly understood. We examined antibody responses in 113 COVID-19 patients and found that severe cases resulting in intubation or death exhibited increased inflammatory markers, lymphopenia, pro-inflammatory cytokines, and high anti-receptor binding domain (RBD) antibody levels. Although anti-RBD immunoglobulin G (IgG) levels generally correlated with neutralization titer, quantitation of neutralization potency revealed that high potency was a predictor of survival. In addition to neutralization of wild-type SARS-CoV-2, patient sera were also able to neutralize the recently emerged SARS-CoV-2 mutant D614G, suggesting cross-protection from reinfection by either strain. However, SARS-CoV-2 sera generally lacked cross-neutralization to a highly homologous pre-emergent bat coronavirus, WIV1-CoV, which has not yet crossed the species barrier. These results highlight the importance of neutralizing humoral immunity on disease progression and the need to develop broadly protective interventions to prevent future coronavirus pandemics.

Practical management of suspected hypersensitivity reactions to anti-tuberculosis drugs.

Tuberculosis (TB) is the commonest cause of death by a single infectious agent globally and ranks amongst the top ten causes of global mortality. The incidence of TB is highest in Low-Middle Income countries (LMICs). Prompt institution of, and compliance with, therapy are cornerstones for a favourable outcome in TB and to mitigate the risk of multiple drug resistant (MDR)-TB, which is challenging to treat. There is some evidence that adverse drug reactions (ADRs) and hypersensitivity reactions (HSRs) to anti-TB drugs occur in over 60% and 3%-4% of patients respectively. Both ADRs and HSRs represent significant barriers to treatment adherence and are recognised risk factors for MDR-TB. HSRs to anti-TB drugs are usually cutaneous and benign, occur within few weeks after commencement of therapy and are likely to be T-cell mediated. Severe and systemic T-cell mediated HSRs and IgE mediated anaphylaxis to anti-TB drugs are relatively rare, but important to recognise and treat promptly. T-cell-mediated HSRs are more frequent amongst patients with co-existing HIV infection. Some patients develop multiple sensitisation to anti-TB drugs. Whilst skin tests, patch tests and in vitro diagnostics have been used in the investigation of HSRs to anti-TB drugs, their predictive value is not established, they are onerous, require specialist input of an allergist and are resource-dependent. This is compounded by the global, unmet demand for allergy specialists, particularly in low-income countries (LICs)/LMICs and now the challenging circumstances of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. This narrative review provides a critical analysis of the limited published evidence on this topic and proposes a cautious and pragmatic approach to optimise and standardise the management of HSRs to anti-TB drugs. This includes clinical risk stratification and a dual strategy involving sequential re-challenge and rapid drug desensitisation. Furthermore, a concerted international effort is needed to generate real-time data on ADRs, HSRs, safety and clinical outcomes of these interventions.

Clinical sensitivity and interpretation of PCR and serological COVID-19 diagnostics for patients presenting to the hospital.

The diagnosis of COVID-19 requires integration of clinical and laboratory data. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic assays play a central role in diagnosis and have fixed technical performance metrics. Interpretation becomes challenging because the clinical sensitivity changes as the virus clears and the immune response emerges. Our goal was to examine the clinical sensitivity of two most common SARS-CoV-2 diagnostic test modalities, polymerase chain reaction (PCR) and serology, over the disease course to provide insight into their clinical interpretation in patients presenting to the hospital. We conducted a single-center, retrospective study. To derive clinical sensitivity of PCR, we identified 209 PCR-positive SARS-CoV-2 patients with multiple PCR test results (624 total PCR tests) and calculated daily sensitivity from date of symptom onset or first positive test. Clinical sensitivity of PCR decreased with days post symptom onset with >90% clinical sensitivity during the first 5 days after symptom onset, 70%-71% from Days 9 to 11, and 30% at Day 21. To calculate daily clinical sensitivity by serology, we utilized 157 PCR-positive patients with a total of 197 specimens tested by enzyme-linked immunosorbent assay for IgM, IgG, and IgA anti-SARS-CoV-2 antibodies. In contrast to PCR, serological sensitivity increased with days post symptom onset with >50% of patients seropositive by at least one antibody isotype after Day 7, >80% after Day 12, and 100% by Day 21. Taken together, PCR and serology are complimentary modalities that require time-dependent interpretation. Superimposition of sensitivities over time indicate that serology can function as a reliable diagnostic aid indicating recent or prior infection.

High Seroprevalence of Anti-SARS-CoV-2 Antibodies in Chelsea, Massachusetts.

SARS-CoV-2 antibody testing allows quantitative determination of disease prevalence, which is especially important in high-risk communities. We performed anonymized convenience sampling of 200 currently asymptomatic residents of Chelsea, the epicenter of COVID-19 illness in Massachusetts, by BioMedomics SARS-CoV-2 combined IgM-IgG point-of-care lateral flow immunoassay. The seroprevalence was 31.5% (17.5% IgM+IgG+, 9.0% IgM+IgG-, and 5.0% IgM-IgG+). Of the 200 participants, 50.5% reported no symptoms in the preceding 4 weeks, of which 24.8% (25/101) were seropositive, and 60% of these were IgM+IgG-. These data are the highest seroprevalence rates observed to date and highlight the significant burden of asymptomatic infection.

Identification of a Th2- and Th17-skewed immune phenotype in chronic urticaria with Th22 reduction dependent on autoimmunity and thyroid disease markers.

BACKGROUND: Chronic urticaria is a condition with many inciting factors and often presents a therapeutic challenge to clinicians. In addition to a central role for mast cells, an immune dysregulated state related to cytokine/chemokine alterations is increasingly being recognized. METHODS: Biopsies of chronic urticaria (n = 11) and normal skin (n = 5) were evaluated with immunostains for CD117, CD3 and dual stains for CD4/T-bet, GATA-3, STAT-3 or BNC-2 (transcription factors specific and mutually exclusive for Th1, Th2, Th17 and Th22 cells, respectively). Clinical data, including autoantibodies and thyroid function tests, and the number of CD117+ mast cells and percent of Th1, Th2, Th17 and Th22 of CD3+ T-cells were compared. RESULTS: Th2 cells and Th17 cells were significantly more frequent in chronic urticaria than controls. In contrast, there was no significant difference in mast cells, Th1 cells or Th22 cells. Three of nine chronic urticaria patients had evidence of autoimmune disease; biopsies from these patients trended toward a greater number of mast cells and decreased percent of Th-cell subtypes as compared with those without autoimmunity markers, with significantly less Th22 cells. CONCLUSIONS: These findings provide novel insight into the role of Th2 and Th17 in chronic urticaria pathophysiology and may impact therapy.

Functionally defective germline variants of sialic acid acetylesterase in autoimmunity.

Sialic acid acetylesterase (SIAE) is an enzyme that negatively regulates B lymphocyte antigen receptor signalling and is required for the maintenance of immunological tolerance in mice. Heterozygous loss-of-function germline rare variants and a homozygous defective polymorphic variant of SIAE were identified in 24/923 subjects of European origin with relatively common autoimmune disorders and in 2/648 controls of European origin. All heterozygous loss-of-function SIAE mutations tested were capable of functioning in a dominant negative manner. A homozygous secretion-defective polymorphic variant of SIAE was catalytically active, lacked the ability to function in a dominant negative manner, and was seen in eight autoimmune subjects but in no control subjects. The odds ratio for inheriting defective SIAE alleles was 8.6 in all autoimmune subjects, 8.3 in subjects with rheumatoid arthritis, and 7.9 in subjects with type I diabetes. Functionally defective SIAE rare and polymorphic variants represent a strong genetic link to susceptibility in relatively common human autoimmune disorders.

Laboratory tests for disorders of complement and complement regulatory proteins.

The complement pathway is a cascade of proteases that is involved in immune surveillance and innate immunity, as well as adaptive immunity. Dysfunction of the complement cascade may be mediated by aberrations in the pathways of activation, complement regulatory proteins, or complement deficiencies, and has been linked to a number of hematologic disorders, including paroxysmal noctural hemoglobinuria (PNH), hereditary angioedema (HAE), and atypical hemolytic-uremic syndrome (aHUS). Here, current laboratory tests for disorders of the complement pathway are reviewed, and their utility and limitations in hematologic disorders and systemic diseases are discussed. Current therapeutic advances targeting the complement pathway in treatment of complement-mediated hematologic disorders are also reviewed.

Laboratory testing in neurorheumatology.

Laboratory testing in cases of neuro-rheumatologic disease can be daunting, and the results can be difficult to interpret if not placed in the correct clinical context. To best help our patients and also to practice in a cost-effective environment, laboratory testing must be performed in a logical manner, guided by symptoms and clinical judgment. The authors discuss the different laboratory tests used in the diagnosis and evaluation of rheumatologic diseases often encountered in the practice of neurology. It is important to understand how the tests are performed and which methods are used at your own institution. Testing should be ordered with a specific diagnosis in mind so as not to confuse the clinical picture with possible false-positive results. Through discussion of the various testing options, the authors advocate a step-wise approach to investigation.

Molecular Diagnostics of Plasma Cell Neoplasms.

Genetic characterization of myeloma at diagnosis by interphase fluorescence in situ hybridization and next-generation sequencing (NGS) can assist with risk stratification and treatment planning. Measurable residual disease (MRD) status after treatment, as evaluated by next-generation flow cytometry or NGS on bone marrow aspirate material, is one of the most important predictors of prognosis. Less-invasive tools for MRD assessment such as liquid biopsy approaches have also recently emerged as potential alternatives.

Use of Clinical Decision Support to Improve the Laboratory Evaluation of Monoclonal Gammopathies.

OBJECTIVES: There is considerable variation in ordering practices for the initial laboratory evaluation of monoclonal gammopathies (MGs) despite clear society guidelines to include serum free light chain (sFLC) testing. We assessed the ability of a clinical decision support (CDS) alert to improve guideline compliance and analyzed its clinical impact. METHODS: We designed and deployed a targeted CDS alert to educate and prompt providers to order an sFLC assay when ordering serum protein electrophoresis (SPEP) testing. RESULTS: The alert was highly effective at increasing the co-ordering of SPEP and sFLC testing. Preimplementation, 62.8% of all SPEP evaluations included sFLC testing, while nearly 90% of evaluations included an sFLC assay postimplementation. In patients with no prior sFLC testing, analysis of sFLC orders prompted by the alert led to the determination that 28.9% (800/2,769) of these patients had an abnormal κ/λ ratio. In 452 of these patients, the sFLC assay provided the only laboratory evidence of a monoclonal protein. Moreover, within this population, there were numerous instances of new diagnoses of multiple myeloma and other MGs. CONCLUSIONS: The CDS alert increased compliance with society guidelines and improved the diagnostic evaluation of patients with suspected MGs.

Human proteins with affinity for dermatan sulfate have the propensity to become autoantigens.

The mystery of why and how a small, seemingly disparate subset of all self molecules become functional autoantigens holds a key to understanding autoimmune diseases. Here and in a companion article in this issue, we show that affinity of self molecules to the glycosaminoglycan dermatan sulfate (DS) is a common property of autoantigens and leads to a specific autoreactive B-1a cell response. Autoimmune ANA/ENA reference sera react preferentially with DS affinity-fractionated cellular proteins. Studying patients with autoimmune diseases, we discovered patient-specific complex autoantigen patterns that are far richer and more diverse than previously thought, indicating significant pathological heterogeneity even within traditionally defined clinical entities, such as systemic lupus erythematosus. By shotgun sequencing of DS affinity-enriched proteomes extracted from cell lines, we identified approximately 200 autoantigens, both novel and previously linked to autoimmunity, including several well-known families of autoantigens related to the nucleosome, ribonucleoproteins, the cytoskeleton, and heat shock proteins. Using electron microscopy, we recognized direct interaction with dead cells as an origin of autoantigenic association of DS with self molecules. DS affinity may be a unifying property of the human autoantigen-ome (ie, totality of self molecules that can serve as functional autoantingens) and thus provides a promising tool for discovery of autoantigens, molecular diagnosis of autoimmune diseases, and development of cause-specific therapies.