Severe Tick-Borne Encephalitis (TBE) in a Patient with X-Linked Agammaglobulinemia; Treatment with TBE Virus IgG Positive Plasma, Clinical Outcome and T Cell Responses.

PURPOSE: A patient with X-linked agammaglobulinemia (XLA) and severe tick-borne encephalitis (TBE) was treated with TBE virus (TBEV) IgG positive plasma. The patient's clinical response, humoral and cellular immune responses were characterized pre- and post-infection. METHODS: ELISA and neutralisation assays were performed on sera and TBEV PCR assay on sera and cerebrospinal fluid. T cell assays were conducted on peripheral blood the patient and five healthy vaccinated controls. RESULTS: The patient was admitted to the hospital with headache and fever. He was not vaccinated against TBE but receiving subcutaneous IgG-replacement therapy (IGRT). TBEV IgG antibodies were low-level positive (due to scIGRT), but the TBEV IgM and TBEV neutralisation tests were negative. During hospitalisation his clinical condition deteriorated (Glasgow coma scale 3/15) and he was treated in the ICU with corticosteroids and external ventricular drainage. He was then treated with plasma containing TBEV IgG without apparent side effects. His symptoms improved within a few days and the TBEV neutralisation test converted to positive. Robust CD8+ T cell responses were observed at three and 18-months post-infection, in the absence of B cells. This was confirmed by tetramers specific for TBEV. CONCLUSION: TBEV IgG-positive plasma given to an XLA patient with TBE without evident adverse reactions may have contributed to a positive clinical outcome. Similar approaches could offer a promising foundation for researching therapeutic options for patients with humoral immunodeficiencies. Importantly, a robust CD8+ T cell response was observed after infection despite the lack of B cells and indicates that these patients can clear acute viral infections and could benefit from future vaccination programs.

In BTK, phosphorylated Y223 in the SH3 domain mirrors catalytic activity, but does not influence biological function.

ABSTRACT: Bruton's tyrosine kinase (BTK) is an enzyme needed for B-cell survival, and its inhibitors have become potent targeted medicines for the treatment of B-cell malignancies. The initial activation event of cytoplasmic protein-tyrosine kinases is the phosphorylation of a conserved regulatory tyrosine in the catalytic domain, which in BTK is represented by tyrosine 551. In addition, the tyrosine 223 (Y223) residue in the SRC homology 3 (SH3) domain has, for more than 2 decades, generally been considered necessary for full enzymatic activity. The initial recognition of its potential importance stems from transformation assays using nonlymphoid cells. To determine the biological significance of this residue, we generated CRISPR-Cas-mediated knockin mice carrying a tyrosine to phenylalanine substitution (Y223F), maintaining aromaticity and bulkiness while prohibiting phosphorylation. Using a battery of assays to study leukocyte subsets and the morphology of lymphoid organs, as well as the humoral immune responses, we were unable to detect any difference between wild-type mice and the Y223F mutant. Mice resistant to irreversible BTK inhibitors, through a cysteine 481 to serine substitution (C481S), served as an additional immunization control and mounted similar humoral immune responses as Y223F and wild-type animals. Collectively, our findings suggest that phosphorylation of Y223 serves as a useful proxy for phosphorylation of phospholipase Cγ2 (PLCG2), the endogenous substrate of BTK. However, in contrast to a frequently held conception, this posttranslational modification is dispensable for the function of BTK.

Memory T cells effectively recognize the SARS-CoV-2 hypermutated BA.2.86 variant.

T cells are critical in mediating the early control of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) breakthrough infection. However, it remains unknown whether memory T cells can effectively cross-recognize new SARS-CoV-2 variants with a broad array of mutations, such as the emergent hypermutated BA.2.86 variant. Here, we report in two separate cohorts, including healthy controls and individuals with chronic lymphocytic leukemia, that SARS-CoV-2 spike-specific CD4+ and CD8+ T cells induced by prior infection or vaccination demonstrate resilient immune recognition of BA.2.86. In both cohorts, we found largely preserved SARS-CoV-2 spike-specific CD4+ and CD8+ T cell magnitudes against mutated spike epitopes of BA.2.86. Functional analysis confirmed that both cytokine expression and proliferative capacity of SARS-CoV-2 spike-specific T cells to BA.2.86-mutated spike epitopes are similarly sustained. In summary, our findings indicate that memory CD4+ and CD8+ T cells continue to provide cell-mediated immune recognition to highly mutated emerging variants such as BA.2.86.

Exposure to Therapeutic BTK Inhibitors Induces Phenocopying of Btk29A Mutants in the Fruit Fly Drosophila melanogaster.

BACKGROUND: Bruton's tyrosine kinase (BTK) is a non-receptor type tyrosine kinase originally identified as the genetic signature responsible for X-linked agammaglobulinemia (XLA) when mutated. Its functional form is required for B lymphocyte maturation in both humans and mice, whereas loss-of-function causes a different form of developmental defect in the fruit fly, Drosophila melanogaster. METHODS: Ibrutinib and other therapeutic inhibitors of BTK have been extensively used to successfully treat various leukemias and lymphomas. Btk29A type 2 is the ortholog of BTK in the fruit fly. We show that feeding wild-type flies an ibrutinib-containing diet induces phenocopying of Btk29A mutants, i.e., failure in the fusion of left and right halves of the dorsal cuticles, partial loss of wing tissues and dysregulation of germ cell production. RESULTS: We have previously reported that Btk29A phosphorylates Drosophila Arm (ß-catenin), and ibrutinib reduces phosphorylation at Tyrosine142 of endogenously expressed ß-catenin in Cos7 cells transfected with Btk29A type 2 cDNA. CONCLUSIONS: Thus, Drosophila is suitable for screens of novel BTK inhibitor candidates and offers a unique in vivo system in which the mode of action of BTK inhibitors can be examined at the molecular, cellular, and organismal levels.

Additive effects of booster mRNA vaccination and SARS-CoV-2 Omicron infection on T cell immunity across immunocompromised states.

Suboptimal immunity to SARS-CoV-2 mRNA vaccination has frequently been observed in individuals with various immunodeficiencies. Given the increased antibody evasion properties of emerging SARS-CoV-2 subvariants, it is necessary to assess whether other components of adaptive immunity generate resilient and protective responses against infection. We assessed T cell responses in 279 individuals, covering five different immunodeficiencies and healthy controls, before and after booster mRNA vaccination, as well as after Omicron infection in a subset of patients. We observed robust and persistent Omicron-reactive T cell responses that increased markedly upon booster vaccination and correlated directly with antibody titers across all patient groups. Poor vaccination responsiveness in immunocompromised or elderly individuals was effectively counteracted by the administration of additional vaccine doses. Functionally, Omicron-reactive T cell responses exhibited a pronounced cytotoxic profile and signs of longevity, characterized by CD45RA+ effector memory subpopulations with stem cell-like properties and increased proliferative capacity. Regardless of underlying immunodeficiency, booster-vaccinated and Omicron-infected individuals appeared protected against severe disease and exhibited enhanced and diversified T cell responses against conserved and Omicron-specific epitopes. Our findings indicate that T cells retain the ability to generate highly functional responses against newly emerging variants, even after repeated antigen exposure and a robust immunological imprint from ancestral SARS-CoV-2 mRNA vaccination.

Real-world assessment of immunogenicity in immunocompromised individuals following SARS-CoV-2 mRNA vaccination: a one-year follow-up of the prospective clinical trial COVAXID.

BACKGROUND: Immunocompromised patients have varying responses to SARS-CoV-2 mRNA vaccination. However, there is limited information available from prospective clinical trial cohorts with respect to long-term immunogenicity-related responses in these patient groups following three or four vaccine doses, and in applicable cases infection. METHODS: In a real-world setting, we assessed the long-term immunogenicity-related responses in patients with primary and secondary immunodeficiencies from the prospective open-label clinical trial COVAXID. The original clinical trial protocol included two vaccine doses given on days 0 and 21, with antibody titres measured at six different timepoints over six months. The study cohort has subsequently been followed for one year with antibody responses evaluated in relation to the third and fourth vaccine dose, and in applicable cases SARS-CoV-2 infection. In total 356/539 patients were included in the extended cohort. Blood samples were analysed for binding antibody titres and neutralisation against the Spike protein for all SARS-CoV-2 variants prevailing during the study period, including Omicron subvariants. SARS-CoV-2 infections that did not require hospital care were recorded through quarterly in-person, or phone-, interviews and assessment of IgG antibody titres against SARS-CoV-2 Nucleocapsid. The original clinical trial was registered in EudraCT (2021-000175-37) and clinicaltrials.gov (NCT04780659). FINDINGS: The third vaccine dose significantly increased Spike IgG titres against all the SARS-CoV-2 variants analysed in all immunocompromised patient groups. Similarly, neutralisation also increased against all variants studied, except for Omicron. Omicron-specific neutralisation, however, increased after a fourth dose as well as after three doses and infection in many of the patient subgroups. Noteworthy, however, while many patient groups mounted strong serological responses after three and four vaccine doses, comparably weak responders were found among patient subgroups with specific primary immunodeficiencies and subgroups with immunosuppressive medication. INTERPRETATION: The study identifies particularly affected patient groups in terms of development of long-term immunity among a larger group of immunocompromised patients. In particular, the results highlight poor vaccine-elicited neutralising responses towards Omicron subvariants in specific subgroups. The results provide additional knowledge of relevance for future vaccination strategies. FUNDING: The present studies were supported by grants from the Swedish Research Council, the Knut and Alice Wallenberg Foundation, Nordstjernan AB, Region Stockholm, and Karolinska Institutet.

Umbilical cord-derived mesenchymal stromal cells preserve endogenous insulin production in type 1 diabetes: a Phase I/II randomised double-blind placebo-controlled trial.

AIM/HYPOTHESIS: This study aimed to investigate the safety and efficacy of treatment with allogeneic Wharton's jelly-derived mesenchymal stromal cells (MSCs) in recent-onset type 1 diabetes. METHODS: A combined Phase I/II trial, composed of a dose escalation followed by a randomised double-blind placebo-controlled study in parallel design, was performed in which treatment with allogeneic MSCs produced as an advanced therapy medicinal product (ProTrans) was compared with placebo in adults with newly diagnosed type 1 diabetes. Inclusion criteria were a diagnosis of type 1 diabetes <2 years before enrolment, age 18-40 years and a fasting plasma C-peptide concentration >0.12 nmol/l. Randomisation was performed with a web-based randomisation system, with a randomisation code created prior to the start of the study. The randomisation was made in blocks, with participants randomised to ProTrans or placebo treatment. Randomisation envelopes were kept at the clinic in a locked room, with study staff opening the envelopes at the baseline visits. All participants and study personnel were blinded to group assignment. The study was conducted at Karolinska University Hospital, Stockholm, Sweden. RESULTS: Three participants were included in each dose cohort during the first part of the study. Fifteen participants were randomised in the second part of the study, with ten participants assigned to ProTrans treatment and five to placebo. All participants were analysed for the primary and secondary outcomes. No serious adverse events related to treatment were observed and, overall, few adverse events (mainly mild upper respiratory tract infections) were reported in the active treatment and placebo arms. The primary efficacy endpoint was defined as Δ-change in C-peptide AUC for a mixed meal tolerance test at 1 year following ProTrans/placebo infusion compared with baseline performance prior to treatment. C-peptide levels in placebo-treated individuals declined by 47%, whereas those in ProTrans-treated individuals declined by only 10% (p<0.05). Similarly, insulin requirements increased in placebo-treated individuals by a median of 10 U/day, whereas insulin needs of ProTrans-treated individuals did not change over the follow-up period of 12 months (p<0.05). CONCLUSIONS/INTERPRETATION: This study suggests that allogeneic Wharton's jelly-derived MSCs (ProTrans) is a safe treatment for recent-onset type 1 diabetes, with the potential to preserve beta cell function. TRIAL REGISTRATION: ClinicalTrials.gov NCT03406585 FUNDING: The sponsor of the clinical trial is NextCell Pharma AB, Stockholm, Sweden.

Large-scale expansions of Friedreich's ataxia GAA•TTC repeats in an experimental human system: role of DNA replication and prevention by LNA-DNA oligonucleotides and PNA oligomers.

Friedreich's ataxia (FRDA) is caused by expansions of GAA•TTC repeats in the first intron of the human FXN gene that occur during both intergenerational transmissions and in somatic cells. Here we describe an experimental system to analyze large-scale repeat expansions in cultured human cells. It employs a shuttle plasmid that can replicate from the SV40 origin in human cells or be stably maintained in S. cerevisiae utilizing ARS4-CEN6. It also contains a selectable cassette allowing us to detect repeat expansions that accumulated in human cells upon plasmid transformation into yeast. We indeed observed massive expansions of GAA•TTC repeats, making it the first genetically tractable experimental system to study large-scale repeat expansions in human cells. Further, GAA•TTC repeats stall replication fork progression, while the frequency of repeat expansions appears to depend on proteins implicated in replication fork stalling, reversal, and restart. Locked nucleic acid (LNA)-DNA mixmer oligonucleotides and peptide nucleic acid (PNA) oligomers, which interfere with triplex formation at GAA•TTC repeats in vitro, prevented the expansion of these repeats in human cells. We hypothesize, therefore, that triplex formation by GAA•TTC repeats stall replication fork progression, ultimately leading to repeat expansions during replication fork restart.

SARS-CoV-2 Antibodies in Commercial Immunoglobulin Products Show Markedly Reduced Cross-reactivities Against Omicron Variants.

PURPOSE: Patients with antibody deficiencies often receive maintenance treatment with donor plasma-derived immunoglobulin (Ig) preparations to decrease the incidence and severity of infections. We have previously shown that IgG antibodies to the original SARS-CoV-2 strain were not consistently present in off-the-shelf Ig batches produced up to approximately 18 months after the first identified case of COVID-19 in the USA and that Ig batches with anti-SARS-CoV-2 IgG primarily contained vaccine-induced spike specific antibodies. This study aimed to investigate the degree of cross-reactivity between vaccine-induced anti-SARS-CoV-2 antibodies against Wuhan strain and subsequent viral variants. METHODS: Samples were collected from 74 Ig batches supplied by three different commercial manufacturers. All batches were used at the Immunodeficiency Unit at the Karolinska University Hospital from the start of the SARS-CoV-2 pandemic until September 2022. Antibody quantity and potential to neutralize virus entry into host cells were assessed against the original SARS-CoV-2 Wuhan strain and the following nine variants: Alpha, Beta, Delta, IHU, and the Omicron BA.1, BA.1.1, BA.1 with spike mutation L452R, BA.2, and BA.3. RESULTS: Ig batches produced approximately 18 months after the SARS-CoV-2 outbreak (from around July 2021) and later consistently contained high quantities of antibodies that bind the Wuhan strain. The Ig batches had overall low reactivity to the SARS-CoV-2 nucleocapsid, which implies that plasma donor spike IgG essentially is the result of vaccination. We assessed the degree of cross-reactivity towards each virus variant by plotting the variant/Wuhan strain ratio, which was consistent regardless of production date, suggesting cross-reactivity with vaccine-induced antibodies rather than virus exposure in the plasma donor population. Viral variants that emerged later during the pandemic systematically had a lower reactivity ratio, except for the Delta and IHU variants. The Ig batches displayed markedly low neutralizing potential towards the Beta variant and all tested Omicron variants. CONCLUSION: Commercial Ig batches currently contain large quantities of SARS-CoV-2 vaccine-induced antibodies. Cross-reactivity with variant strains is evident but varies, with markedly low neutralizing potential observed against Omicron variants.

Chemical Modifications and Design Influence the Potency of Huntingtin Anti-Gene Oligonucleotides.

Huntington's disease is a neurodegenerative, trinucleotide repeat (TNR) disorder affecting both males and females. It is caused by an abnormal increase in the length of CAG•CTG TNR in exon 1 of the Huntingtin gene (HTT). The resultant, mutant HTT mRNA and protein cause neuronal toxicity, suggesting that reduction of their levels would constitute a promising therapeutic approach. We previously reported a novel strategy in which chemically modified oligonucleotides (ONs) directly target chromosomal DNA. These anti-gene ONs were able to downregulate both HTT mRNA and protein. In this study, various locked nucleic acid (LNA)/DNA mixmer anti-gene ONs were tested to investigate the effects of varying ON length, LNA content, and fatty acid modification on HTT expression. Altering the length did not significantly influence the ON potency, while LNA content was critical for activity. Utilization of palmitoyl-modified LNA monomers enhanced the ON activity relatively to the corresponding nonmodified LNA under serum starvation conditions. Furthermore, the number of palmitoylated LNA monomers and their positioning greatly affected ON potency. In addition, we performed RNA sequencing analysis, which showed that the anti-gene ONs affect the "immune system process, mRNA processing, and neurogenesis." Furthermore, we observed that for repeat containing genes, there is a higher tendency for antisense off-targeting. Taken together, our findings provide an optimized design of anti-gene ONs that could potentially be developed as DNA-targeting therapeutics for this class of TNR-related diseases.

Pirtobrutinib targets BTK C481S in ibrutinib-resistant CLL but second-site BTK mutations lead to resistance.

Covalent inhibitors of Bruton tyrosine kinase (BTK) have transformed the therapy of chronic lymphocytic leukemia (CLL), but continuous therapy has been complicated by the development of resistance. The most common resistance mechanism in patients whose disease progresses on covalent BTK inhibitors (BTKis) is a mutation in the BTK 481 cysteine residue to which the inhibitors bind covalently. Pirtobrutinib is a highly selective, noncovalent BTKi with substantial clinical activity in patients whose disease has progressed on covalent BTKi, regardless of BTK mutation status. Using in vitro ibrutinib-resistant models and cells from patients with CLL, we show that pirtobrutinib potently inhibits BTK-mediated functions including B-cell receptor (BCR) signaling, cell viability, and CCL3/CCL4 chemokine production in both BTK wild-type and C481S mutant CLL cells. We demonstrate that primary CLL cells from responding patients on the pirtobrutinib trial show reduced BCR signaling, cell survival, and CCL3/CCL4 chemokine secretion. At time of progression, these primary CLL cells show increasing resistance to pirtobrutinib in signaling inhibition, cell viability, and cytokine production. We employed longitudinal whole-exome sequencing on 2 patients whose disease progressed on pirtobrutinib and identified selection of alternative-site BTK mutations, providing clinical evidence that secondary BTK mutations lead to resistance to noncovalent BTKis.

Specific properties of shRNA-mediated CCR5 downregulation that enhance the inhibition of HIV-1 infection in combination with shRNA targeting HIV-1 rev.

Treatment with RNAi against HIV-1 transcripts efficiently inhibits viral replication but induces selection of escape mutants; therefore, the CCR5 coreceptor was suggested as an additional target. Blocking viral and host transcripts improved the antiviral effect. We have used short hairpin RNA (shRNA) targeting the human CCR5 (shCCR5) or the HIV-1 rev (shRev) transcripts to demonstrate distinctive properties of anti-CCR5 shRNA: shCCR5 induced more sustained protection than shRev; partial reduction in CCR5 expression substantially decreased HIV-1 infection, and shCCR5 performed better than shRev in the mixed shRNA-treated and untreated cultures. These observations indicate that CCR5 inhibitors should be conveniently included in HIV-1 gene silencing treatment schedules when only a certain cell fraction is protected to further reduce endogenous virus in a properly ART-treated HIV-1 infected individual.

Immunodeficiency syndromes differentially impact the functional profile of SARS-CoV-2-specific T cells elicited by mRNA vaccination.

Many immunocompromised patients mount suboptimal humoral immunity after SARS-CoV-2 mRNA vaccination. Here, we assessed the single-cell profile of SARS-CoV-2-specific T cells post-mRNA vaccination in healthy individuals and patients with various forms of immunodeficiencies. Impaired vaccine-induced cell-mediated immunity was observed in many immunocompromised patients, particularly in solid-organ transplant and chronic lymphocytic leukemia patients. Notably, individuals with an inherited lack of mature B cells, i.e., X-linked agammaglobulinemia (XLA) displayed highly functional spike-specific T cell responses. Single-cell RNA-sequencing further revealed that mRNA vaccination induced a broad functional spectrum of spike-specific CD4+ and CD8+ T cells in healthy individuals and patients with XLA. These responses were founded on polyclonal repertoires of CD4+ T cells and robust expansions of oligoclonal effector-memory CD45RA+ CD8+ T cells with stem-like characteristics. Collectively, our data provide the functional continuum of SARS-CoV-2-specific T cell responses post-mRNA vaccination, highlighting that cell-mediated immunity is of variable functional quality across immunodeficiency syndromes.

Estimating the number of diseases - the concept of rare, ultra-rare, and hyper-rare.

At the dawn of the personalized medicine era, the number of rare diseases has been estimated at 10,000. By considering the influence of environmental factors together with genetic variations and our improved diagnostic capabilities, an assessment suggests a considerably larger number. The majority would be extremely rare, and hence, we introduce the term "hyper-rare," defined as affecting <1/108 individuals. Such disorders would potentially outnumber all currently known rare diseases. Because autosomal recessive disorders are likely concentrated in consanguineous populations, and rare toxicities in rural areas, establishing their existence necessitates a greater reach than is currently viable. Moreover, the randomness of X-linked and gain-of-function mutations greatly compound this challenge. However, whether concurrent diseases actually cause a distinct illness will depend on if their pathological mechanisms interact (phenotype conversion) or not (phenotype maintenance). The hyper-rare disease concept will be important in precision medicine with improved diagnosis and treatment of rare disease patients.

Respiratory viral infections in otherwise healthy humans with inherited IRF7 deficiency.

Autosomal recessive IRF7 deficiency was previously reported in three patients with single critical influenza or COVID-19 pneumonia episodes. The patients' fibroblasts and plasmacytoid dendritic cells produced no detectable type I and III IFNs, except IFN-ß. Having discovered four new patients, we describe the genetic, immunological, and clinical features of seven IRF7-deficient patients from six families and five ancestries. Five were homozygous and two were compound heterozygous for IRF7 variants. Patients typically had one episode of pulmonary viral disease. Age at onset was surprisingly broad, from 6 mo to 50 yr (mean age 29 yr). The respiratory viruses implicated included SARS-CoV-2, influenza virus, respiratory syncytial virus, and adenovirus. Serological analyses indicated previous infections with many common viruses. Cellular analyses revealed strong antiviral immunity and expanded populations of influenza- and SARS-CoV-2-specific memory CD4+ and CD8+ T cells. IRF7-deficient individuals are prone to viral infections of the respiratory tract but are otherwise healthy, potentially due to residual IFN-ß and compensatory adaptive immunity.

MAIT cell compartment characteristics are associated with the immune response magnitude to the BNT162b2 mRNA anti-SARS-CoV-2 vaccine.

Mucosa-associated invariant T (MAIT) cells are unconventional T cells with innate-like capacity to rapidly respond to microbial infection via MR1-restricted antigen recognition. Emerging evidence indicate that they can also act as rapid sensors of viral infection via innate cytokine activation. However, their possible role in the immune response to mRNA vaccination is unknown. Here, we evaluated the involvement of MAIT cells in individuals vaccinated with the BNT162b2 mRNA SARS-CoV-2 vaccine. MAIT cell levels, phenotype and function in circulation were preserved and unperturbed through day 35 post-vaccination in healthy donor (HD) vaccinees, as well as people living with HIV (PLWH) or with primary immunodeficiency (PID). Unexpectedly, pre-vaccination and post-vaccination levels of MAIT cells correlated positively with the magnitude of the SARS-CoV-2 spike protein-specific CD4 T cell and antibody responses in the HD vaccinees. This pattern was largely preserved in the PID group, but less so in the PLWH group. Furthermore, in the HD vaccinees levels of MAIT cell activation and cytolytic potential correlated negatively to the adaptive antigen-specific immune responses. These findings indicate an unexpected association between MAIT cell compartment characteristics and the immune response magnitude to the BNT162b2 mRNA vaccine.

Neutralizing SARS-CoV-2 Antibodies in Commercial Immunoglobulin Products Give Patients with X-Linked Agammaglobulinemia Limited Passive Immunity to the Omicron Variant.

Immunodeficient individuals often rely on donor-derived immunoglobulin (Ig) replacement therapy (IGRT) to prevent infections. The passive immunity obtained by IGRT is limited and reflects the state of immunity in the plasma donor population at the time of donation. The objective of the current study was to describe how the potential of passive immunity to SARS-CoV-2 in commercial off-the-shelf Ig products used for IGRT has evolved during the pandemic. Samples were collected from all consecutive Ig batches (n = 60) from three Ig producers used at the Immunodeficiency Unit at Karolinska University Hospital from the start of the SARS-CoV-2 pandemic until January 2022. SARS-CoV-2 antibody concentrations and neutralizing capacity were assessed in all samples. In vivo relevance was assessed by sampling patients with XLA (n = 4), lacking endogenous immunoglobulin synthesis and on continuous Ig substitution, for plasma SARS-CoV-2 antibody concentration. SARS-CoV-2 antibody concentrations in commercial Ig products increased over time but remained inconsistently present. Moreover, Ig batches with high neutralizing capacity towards the Wuhan-strain of SARS-CoV-2 had 32-fold lower activity against the Omicron variant. Despite increasing SARS-CoV-2 antibody concentrations in commercial Ig products, four XLA patients on IGRT had relatively low plasma concentrations of SARS-CoV-2 antibodies with no potential to neutralize the Omicron variant in vitro. In line with this observation, three out the four XLA patients had symptomatic COVID-19 during the Omicron wave. In conclusion, 2 years into the pandemic the amounts of antibodies to SARS-CoV-2 vary considerably among commercial Ig batches obtained from three commercial producers. Importantly, in batches with high concentrations of antibodies directed against the original virus strain, protective passive immunity to the Omicron variant appears to be insufficient.

Elevated CD21low B Cell Frequency Is a Marker of Poor Immunity to Pfizer-BioNTech BNT162b2 mRNA Vaccine Against SARS-CoV-2 in Patients with Common Variable Immunodeficiency.

PURPOSE: Limited data is available on the effect of COVID-19 vaccination in immunocompromised individuals. Here, we provide the results from vaccinating a single-center cohort of patients with common variable immunodeficiency (CVID). METHODS: In a prospective, open-label clinical trial, 50 patients with CVID and 90 age-matched healthy controls (HC) were analyzed for SARS-CoV-2 spike antibody (Ab) production after one or two doses of the Pfizer-BioNTech BNT162b2 mRNA vaccine. Additionally, in selected patients, SARS-CoV-2 spike-specific T-cells were assessed. RESULTS: A potent vaccine-induced anti-spike-specific IgG Ab response was observed in all the HC. In contrast, only 68.3% of the CVID patients seroconverted, with median titers of specific Ab being 83-fold lower than in HC. In fact, only 4/46 patients (8.6%) of patients who were seronegative at baseline reached the threshold for an optimal response (250 U/mL). Using the EUROclass definition, patients with either a reduced proportion, but not absolute counts, of switched memory B-cells or having an increased frequency of CD21low B-cells generally generated poor vaccine responses. Overall, CVID-patients had reduced spike-specific IFN-γ positive CD4+ T cell responses 2 weeks after the second dose, compared to HC. The total CD4 and CD4 central memory cell counts correlated with humoral immunity to the vaccine. CONCLUSIONS: CVID patients with low frequency of switched memory B-cells or an increased frequency of CD21low B-cells according to the EUROclass definition demonstrated poor responses to Pfizer-BioNTech BNT162b2 mRNA vaccination. Cellular immune responses were significantly affected, affirming that the defect in CVID is not limited to humoral immunity.