Limitations in the clinical utility of vaccine challenge responses in the evaluation of primary antibody deficiency including Common Variable Immunodeficiency Disorders.

Vaccine challenge responses are an integral component in the diagnostic evaluation of patients with primary antibody deficiency, including Common Variable Immunodeficiency Disorders (CVID). There are no studies of vaccine challenge responses in primary hypogammaglobulinemia patients not accepted for subcutaneous/intravenous immunoglobulin (SCIG/IVIG) replacement compared to those accepted for such treatment. Vaccine challenge responses in patients enrolled in two long-term prospective cohorts, the New Zealand Hypogammaglobulinemia Study (NZHS) and the New Zealand CVID study (NZCS), were compared in this analysis. Almost all patients in the more severely affected SCIG/IVIG treatment group achieved protective antibody levels to tetanus toxoid and H. influenzae type B (HIB). Although there was a highly significant statistical difference in vaccine responses to HIB, tetanus and diphtheria toxoids, there was substantial overlap in both groups. In contrast, there was no significant difference in Pneumococcal Polysaccharide antibody responses to Pneumovax® (PPV23). This analysis illustrates the limitations of evaluating vaccine challenge responses in patients with primary hypogammaglobulinemia to establish the diagnosis of CVID and in making decisions to treat with SCIG/IVIG. The conclusion from this study is that patients with symptoms attributable to primary hypogammaglobulinemia with reduced IgG should not be denied SCIG/IVIG if they have normal vaccine responses.

Discordant Phenotypes of Nephritis in Patients with X-linked Agammaglobulinemia.

PURPOSE: To define the clinical and histological characteristics of nephritis in patients with X-linked agammaglobulinemia (XLA) and their immunological profiles. METHODS: The clinical, immunological, and histological findings of nine patients with XLA and nephritis were retrospectively analyzed. RESULTS: Based on kidney histological findings, patients with XLA and nephritis could be divided into two groups, viz., chronic glomerulonephritis (CGN) and tubulointerstitial nephritis (TIN). The two groups showed different immunological profiles. Patients in the CGN group exhibited an atypical immunological profile of XLA, with pathogenic leaky B cells producing immunoglobulins that may play a role in forming immune complexes and causing immune-mediated glomerulonephritis. In contrast, patients in the TIN group exhibited a typical immunological profile of XLA, suggesting that antibody-independent/other BTK-dependent mechanisms, or immunoglobulin replacement therapy (IgRT)-related immune/nonimmune-mediated nephrotoxicity causes TIN. CONCLUSION: Nephritis occurring in patients with XLA could have links between their renal pathology and immunological status. Careful observation is recommended to detect kidney pathology in patients with XLA on IgRT.

Case report: Persistent hypogammaglobulinemia and mixed chimerism after HLA class-II disparate-hematopoietic stem cell transplant.

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative treatment for various hematological, immunological and metabolic diseases, replacing the patient's hematopoietic system with donor-derived healthy hematopoietic stem cells. HSCT can be complicated by early and late events related to impaired immunological recovery such as prolonged hypogammaglobulinemia post-HSCT. We present a 16-year-old female patient with sickle-cell disease who underwent HSCT with stem cells from a human leukocyte antigen (HLA) class-II mismatched family donor. While cellular recovery was good post-HSCT, the patient developed mixed chimerism and suffered from cervical lymphadenopathy, recurrent airway infections and cutaneous SLE. She presented with hypogammaglobulinemia and was started on immunoglobulin substitution therapy and antibiotic prophylaxis. B-cell phenotyping showed that she had increased transitional and naïve mature B cells, reduced memory B cells, and diminished marginal zone/natural effector cells. In-depth immunophenotyping and B-cell receptor repertoire sequencing ruled out an intrinsic B-cell defect by expression of activation-induced cytidine deaminase (AID), presence of somatic hypermutations and differentiation into IgG- and IgA-producing plasma cells in vitro. Immunohistochemistry and flow cytometry of lymph node tissue showed a clear block in terminal B-cell differentiation. Chimerism analysis of sorted lymph node populations showed that exclusively patient-derived B cells populated germinal centers, while only a minor fraction of follicular helper T cells was patient-derived. Given this discrepancy, we deduced that the HLA class-II disparity between patient and donor likely hinders terminal B-cell differentiation in the lymph node. This case highlights that studying disturbed cognate T-B interactions in the secondary lymphoid organs can provide unique insights when deciphering prolonged hypogammaglobulinemia post-HSCT.

Transient hypogammaglobulinemia of infancy and unclassified syndromic immunodeficiencies are highly common in oesophageal atresia patients.

Due to the high rate of post-operative sepsis and other infectious complications, a routine immunological screening protocol has been initiated since 2015 in our paediatric surgery clinic for all patients admitted with oesophageal atresia (EA) and warrant a delayed definitive treatment. In our study, we aimed to evaluate the immunodeficiencies in EA patients, by comparing them to healthy age-matched controls. As a prospective cohort study, EA patients admitted between 2015 and 2022, who had their definitive operation after the newborn period (>28 days of age) were included. On admission, serum concentrations of IgG, IgA, IgM, lymphocyte subset levels, C3 and C4 levels, specific IgG antibody responses against hepatitis B, hepatitis A, measles, varicella zoster were evaluated. The patients were age-matched with healthy controls to compare the results and followed up until three years of age. If a humoral immunodeficiency was detected, intravenous immunoglobulin treatment was administered before major oesophageal surgery and during follow-up. 31 EA patients (18 M/13F) with a mean age of 13.3 ± 9.0 months were compared with 40 age-matched healthy controls. Mean serum IgG levels were found to be statistically lower than controls in all age groups (P < .05). Transient hypogammaglobulinemia of infancy (THI) and unclassified syndromic immunodeficiencies (USI) were found to be strikingly high, accounting for 29.0% and 22.5%, respectively, adding up to 51.5% of EA patients. This is the first study evaluating immunodeficiencies in EA patients found in the reviewed literature. More than half of EA patients that required delayed surgery had humoral immunodeficiency, so preoperative screening and immunology referral may improve patient outcomes.

IgG replacement in multiple myeloma.

T cell engagers (TCE) such as chimeric antigen receptor (CAR) T cell therapy and bispecific antibodies (BiAbs) for the treatment of multiple myeloma (MM) have significantly improved clinical outcomes, but have also raised awareness for ensuing post-treatment secondary immunodeficiency and hypogammaglobulinemia (HG). As patients with MM live longer, recurrent infections become a significant component of therapy-associated morbidity and mortality. Treatment of HG with immunoglobulin G replacement therapy (IgG-RT) has been a mainstay of the primary immunodeficiency (PI) world, and extrapolation to MM has recently started to show promising clinical outcomes. However, IgG-RT initiation, dosing, route, timing, monitoring, and management in MM has not been standardized in the setting of TCE. Progress in MM treatment will involve greater recognition and screening of underlying secondary immunodeficiency, identification of risk-stratification markers, optimizing IgG-RT management, and implementing other approaches to decrease the risk of infection. In this review, we summarize infection risk, risk of HG, and management strategies for IgG-RT in patients with relapsed MM after TCE.

Analysis of LRBA pathogenic variants and the association with functional protein domains and clinical presentation.

LRBA is a cytoplasmic protein that is ubiquitously distributed. Almost all LRBA domains have a scaffolding function. In 2012, it was reported that homozygous variants in LRBA are associated with early-onset hypogammaglobulinemia. Since its discovery, more than 100 pathogenic variants have been reported. This review focuses on the variants reported in LRBA and their possible associations with clinical phenotypes. In this work LRBA deficiency cases reported more than 11 years ago have been revised. A database was constructed to analyze the type of variants, age at onset, clinical diagnosis, infections, autoimmune diseases, and cellular and immunoglobulin levels. The review of cases from 2012 to 2023 showed that LRBA deficiency was commonly diagnosed in patients with a clinical diagnosis of Common Variable Immunodeficiency, followed by enteropathy, neonatal diabetes mellitus, ALPS, and X-linked-like syndrome. Most cases show early onset of presentation at <6 years of age. Most cases lack protein expression, whereas hypogammaglobulinemia is observed in half of the cases, and IgG and IgA levels are isotypes reported at low levels. Patients with elevated IgG levels exhibited more than one autoimmune manifestation. Patients carrying pathogenic variants leading to a premature stop codon show a severe phenotype as they have an earlier onset of disease presentation, severe autoimmune manifestations, premature death, and low B cells and regulatory T cell levels. Missense variants were more common in patients with low IgG levels and cytopenia. This work lead to the conclusion that the type of variant in LRBA has association with disease severity, which leads to a premature stop codon being the ones that correlates with severe disease.

Hypogammaglobulinemia Class G Is Present in Compensated and Decompensated Patients with Propionate Defects, Independent of Their Nutritional Status.

Propionate defects (PDs) mainly include methylmalonic (MMA) and propionic acidemia (PA) defects. Lifelong PD patients progress from the compensated to the decompensated stages, the latter of which are characterized by life-threatening acidemia and hyperammonemia crises. PD patients can suffer immunocompromise, especially during the decompensation stage. There is a significant gap in the research regarding the humoral immune response in PD patients. Here, we analyzed serum immunoglobulin concentrations and hemograms across compensated and decompensated stages in PD patients. Nutritional status and crisis triggers of decompensation were also explored. Twenty patients were studied, and 25 decompensation events (DE) and 8 compensation events (CE) were recorded. Compared with those in the CE group, the IgG levels in the DE group (513.4 ± 244.5 mg/dL) were significantly lower than those in the CE group (860.8 ± 456.5 mg/dL) (p < 0.0087). The mean hemoglobin concentration was significantly lower in the DE group (11.8 g/dL) than in the CE group (13.4 g/dL) (p < 0.05). The most frequent (48%) possible decompensation trigger factor was infection. Most of the events were registered in eutrophic patients (87.9%), despite which 65.2% and 50% of patients who experienced decompensated and compensated events, respectively, presented with hypogammaglobulinemia G. These findings provide evidence of the immunodeficiency of PD patients, independent of their nutritional status. We suggest that PD patients be managed as immunocompromised independently of their nutritional status or metabolic state (compensated or decompensated).

Clinical efficacy of SARS-CoV-2 Omicron-neutralizing antibodies in immunoglobulin preparations for the treatment of agammaglobulinemia in patients with primary antibody deficiency.

Immunocompromised individuals are at significantly elevated risk for severe courses of coronavirus disease 2019 (COVID-19). In addition to vaccination, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) neutralizing antibodies (nAbs) have been applied throughout the pandemic, with time of treatment onset and potency against the currently prevailing virus variant identified as relevant factors for medical benefit. Using data from the European Society for Immunodeficiencies (ESID) registry, the present study evaluated COVID-19 cases in three groups of patients with inborn errors of immunity (IEI; 981 agammaglobulinemia patients on immunoglobulin replacement therapy (IGRT); 8960 non-agammaglobulinemia patients on IGRT; 14 428 patients without IGRT), and the neutralizing capacity of 1100 immunoglobulin lots against SARS-CoV-2 ("Wuhan" and Omicron strains), throughout 3 years. From the first (2020/2021) to the second (2021/2022) cold season, i.e., during the virus drift to the more contagious Omicron variants, an increase in case numbers was recorded that was comparable (~2- to 3-fold) for all three study groups. During the same period, immunoglobulin lots showed a profound nAb increase against the archetypal SARS-CoV-2 strain, yet only low levels of Omicron nAbs. Notably, shortly before the third (2022/2023) cold season, Omicron-neutralizing capacity of released immunoglobulin lots had plateaued at high levels. From the second to the third cold season, COVID-19 cases dropped markedly. While a ~6-fold case reduction was recorded for the groups of non-agammaglobulinemia patients on IGRT and IEI patients not receiving IGRT, the decline was ~30-fold for the group of agammaglobulinemia patients on IGRT. These findings suggest a substantial COVID-19-protective effect of IGRT, at least for distinct groups of antibody-deficient patients.

The time-dependent changes in serum immunoglobulin after kidney transplantation and its association with infection.

Introduction: Kidney transplant recipients often experience significant alterations in their immune system, which can lead to increased susceptibility to infections. This study aimed to analyze time-dependent changes in serum immunoglobulin and complement levels and determine the risk factors associated with infection. Methods: A retrospective analysis of serum samples from 192 kidney transplant recipients who received transplantations between August 2016 and December 2019 was conducted. The serum samples were obtained at preoperative baseline (T0), postoperative 2 weeks (T1), 3 months (T2), and 1 year (T3). The levels of serum C3, C4, IgG, IgA, and IgM were measured to evaluate immune status over time. Results: The analysis revealed significant decreases in IgG and IgA levels at T1. This period was associated with the highest occurrence of hypogammaglobulinemia (HGG) and hypocomplementemia (HCC), as well as an increased incidence of severe infection requiring hospitalization and graft-related viral infections. Using a time-dependent Cox proportional hazards model adjusted for time-varying confounders, HGG was significantly associated with an increased risk of infection requiring hospitalization (HR, 1.895; 95% CI: 1.871-1.920, P-value<0.001) and graft-related viral infection (HR, 1.152; 95% CI: 1.144-1.160, P-value<0.001). Discussion: The findings suggest that monitoring serum immunoglobulin levels post-transplant provides valuable insights into the degree of immunosuppression. Hypogammaglobulinemia during the early post-transplant period emerges as a critical risk factor for infection, indicating that serum immunoglobulins could serve as feasible biomarkers for assessing infection risk in kidney transplant recipients.

Baseline immunoglobulin G and immune function in non-Hodgkin lymphoma: a retrospective analysis.

Introduction: Non-Hodgkin's lymphoma (NHL) encompasses a diverse group of lymphoma subtypes with a wide range in disease course. Previous studies show that hypogammaglobulinemia in treatment-naïve patients is associated with poorer survival in high grade B-cell non-Hodgkin's lymphomas, though it is not known how this applies across all B-cell lymphoid malignancies. Methods: We conducted a retrospective study of immunoglobulin levels and clinical outcomes including survival, hospitalization, and infection rates in patients diagnosed with B-cell non-Hodgkin lymphomas of all grades at our institution. Results: Two-hundred twenty-three adults (aged = 18 years) with available pre-treatment IgG levels were selected, with hypogammaglobulinemia defined as IgG< 500 mg/mL. For this analysis, we grouped DLBCL (n=90), Primary CNS (n=5), and Burkitt lymphoma (n=1) together as high-grade, while CLL (n=52), mantle cell (n=20), marginal zone (n=25), follicular (n=21), and Waldenstrom macroglobulinemia (n=5) were low-grade. The incidence of hypogammaglobulinemia in our cohort of both high and low-grade lymphoma patients was 13.5% (n=30). Across all NHL subtypes, individuals with baseline IgG< 500 mg/dL showed an increased rate of hospitalization (4.453, CI: 1.955-10.54, p= 0.0005) and higher mortality (3.325, CI: 1.258, 8.491, p= 0.013), yet no association in number of infections when compared with those with IgG=500 mg/dL. There was a higher hospitalization rate (3.237, CI: 1.77-6.051, p=0.0017) in those with high-grade lymphoma with hypogammaglobulinemia when compared with low-grade. There was no statistically significant difference in individuals who were alive after three years in those with baseline IgG<500 mg/dL. Discussion: Our study is the first to analyze incidence of hypogammaglobulinemia at the time of diagnosis of NHL as a potential biomarker of interest for future outcomes including hospitalization and infection.

Viral infections and inborn errors of immunity.

PURPOSE OF REVIEW: The purpose of this focused review is to discuss unusual presentations of viral infections in the context of specific inborn errors of immunity. We will discuss hyper immunoglobulin E (IgE) syndromes, epidermodysplasia verruciformis, and X-linked agammaglobulinemia as examples of inborn errors of immunity associated with specific presentations of viral infection and disease. RECENT FINDINGS: Advances in both genetic and viral diagnostics have broadened our understanding of viral pathogenesis in the setting of immune dysfunction and the variable phenotype of inborn errors of immunity. Dedicator of cytokinesis 8 (DOCK8) deficiency is now recognized as an inborn error of immunity within the hyper IgE syndrome phenotype and is associated with unusually aggressive cutaneous disease caused by herpes simplex and other viruses. Studies of patients with epidermodysplasia verruciformis have proven that rarely detected human papillomavirus subtypes may cause malignancy in the absence of adequate host defenses. Finally, patients with X-linked agammaglobulinemia may remain at risk for severe and chronic viral infections, even as immune globulin supplementation reduces the risk of bacterial infection. SUMMARY: Susceptibility to viral infections in patients with inborn errors of immunity is conferred by specific, molecular defects. Recurrent, severe, or otherwise unusual presentations of viral disease should prompt investigation for an underlying genetic defect.

Heterozygous SERPINA1 Defects and Their Impact on Clinical Manifestations of Patients with Predominantly Antibody Deficiencies.

Patients with predominantly antibody deficiencies (PADs) display hypogammaglobulinemia with a high prevalence of infections, along with autoimmune manifestations, benign and malignant lymphoproliferation and granulomatous disease. It is noteworthy that PAD patients, even those with defects in the same causative genes, display a variable clinical phenotype, suggesting that additional genetic polymorphisms, located in either immune-related or non-immune-related genes, may affect their clinical and laboratory phenotype. In this context, we analyzed 80 PAD patients, including 70 with common variable immunodeficiency (CVID) for SERPINA1 defects, in order to investigate the possible contribution to PAD clinical phenotype. Ten CVID patients carried heterozygous pathogenic SERPINA1 defects with normal alpha-1 antitrypsin levels. Interestingly, the presence of the Z allele (rs28929474), which was found in three patients, was significantly associated with liver disease; hepatic complications were also observed in patients carrying the p.Leu23Gln (rs1379209512) and the p.Phe76del (rs775982338) alleles. Conversely, no correlation of SERPINA1 defective variants with respiratory complications was observed, although patients with pathogenic variants exhibit a reduced probability of developing autoimmune diseases. Therefore, we recommend SERPINA1 genetic analysis in PAD in order to identify patients with a higher risk for liver disease.

Severe enterovirus infections in patients with immune-mediated inflammatory diseases receiving anti-CD20 monoclonal antibodies.

OBJECTIVE: Patients with X linked agammaglobulinemia are susceptible to enterovirus (EV) infections. Similarly, severe EV infections have been described in patients with impaired B-cell response following treatment with anti-CD20 monoclonal antibodies (mAbs), mostly in those treated for haematological malignancies. We aimed to describe severe EV infections in patients receiving anti-CD20 mAbs for immune-mediated inflammatory diseases (IMIDs). METHODS: Patients were included following a screening of data collected through the routine surveillance of EV infections coordinated by the National Reference Center and a review of the literature. Additionally, neutralising antibodies were assessed in a patient with chronic EV-A71 meningoencephalitis. RESULTS: Nine original and 17 previously published cases were retrieved. Meningoencephalitis (n=21/26, 81%) associated with EV-positive cerebrospinal fluid (n=20/22, 91%) was the most common manifestation. The mortality rate was high (27%). EV was the only causal agents in all reported cases. Patients received multiple anti-CD20 mAbs infusions (median 8 (5-10)), resulting in complete B-cell depletion and moderate hypogammaglobulinemia (median 4.9 g/L (4.3-6.7)), and had limited concomitant immunosuppressive treatments. Finally, in a patient with EV-A71 meningoencephalitis, a lack of B-cell response to EV was shown. CONCLUSION: EV infection should be evoked in patients with IMIDs presenting with atypical organ involvement, especially meningoencephalitis. Anti-CD20 mAbs may lead to impaired B-cell response against EV, although an underlying primary immunodeficiency should systematically be discussed.

A Nationwide Study of the Delayed Diagnosis and the Clinical Manifestations of Predominantly Antibody Deficiencies and CTLA4-Mediated Immune Dysregulation Syndrome in Greece.

Background and Objectives: Predominantly antibody deficiencies (PAD) represent the most common type of primary immunodeficiencies in humans, characterized by a wide variation in disease onset, clinical manifestations, and outcome. Considering that the prevalence of PAD in Greece is unknown, and there is limited knowledge on the clinical and laboratory characteristics of affected patients, we conducted a nationwide study. Materials and Methods: 153 patients (male/female: 66/87; median age: 43.0 years; range: 7.0-77.0) diagnosed, and followed-up between August 1979 to September 2023. Furthermore, we classified our cohort into five groups according to their medical history, immunoglobulin levels, and CTLA4-mutational status: 123 had common variable immunodeficiency (CVID), 12 patients with "secondary" hypogammaglobulinemia due to a previous B-cell depletion immunotherapy for autoimmune or malignant disease several years ago (median: 9 years, range 6-14) displaying a typical CVID phenotype, 7 with combined IgA and IgG subclass deficiencies, 5 patients with CVID-like disease due to CTLA4-mediated immune dysregulation syndrome, and 6 patients with unclassified hypogammaglobulinemia. Results: We demonstrated a remarkable delay in PAD diagnosis, several years after the onset of related symptoms (median: 9.0 years, range: 0-43.0). A family history of PAD was only present in 11.8%, with the majority of patients considered sporadic cases. Most patients were diagnosed in the context of a diagnostic work-up for recurrent infections, or recurrent/resistant autoimmune cytopenias. Interestingly, 10 patients (5.6%) had no history of infection, diagnosed due to either recurrent/resistant autoimmunity, or during a work-up of their medical/family history. Remarkable findings included an increased prevalence of lymphoproliferation (60.1%), while 39 patients (25.5%) developed bronchiectasis, and 16 (10.5%) granulomatous disease. Cancer was a common complication in our cohort (25 patients, 16.3%), with B-cell malignancies representing the most common neoplasms (56.7%). Conclusion: Our findings indicate the necessity of awareness about PAD and their complications, aiming for early diagnosis and the appropriate management of affected patients.

Follow-up of immune response in patients with common variable immunodeficiency following SARS-CoV-2 vaccination.

The COVID-19 pandemic highlighted the importance of effective vaccination strategies in controlling the spread of infectious diseases. SARS-CoV-2 vaccine has demonstrated high efficacy in preventing COVID-19 infection in the general population. However, the efficacy of this vaccine in patients with predominantly antibody deficiencies, such as common variable immunodeficiency (CVID) and X-linked agammaglobulinemia (XLA), should be closely monitored. CVID and XLA are rare genetic disorders that impair the immune system's ability to produce antibodies, which are crucial for fighting infections. Patients with these disorders have a higher risk of severe disease and mortality from COVID-19 due to their compromised immune systems. In this study, we evaluated the humoral and cellular immune responses after four doses of mRNA-1273 and one BNT162b2 bivalent vaccine in a cohort of patients with CVID and XLA. The response in this population was lower than in the control group. However, the administration of the third dose improved the number of patients with seroconversion and the intensity of the humoral response, as well as the number of patients with a positive cellular response. Finally, the administration of the fourth and fifth doses improves the antibody titer and neutralization against wild type variant, but not against the prevalent XBB1.5 variant.

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.

B-cells absence in patients diagnosed as inborn errors of immunity: a registry-based study.

Hypogammaglobulinemia without B-cells is a subgroup of inborn errors of immunity (IEI) which is characterized by a significant decline in all serum immunoglobulin isotypes, coupled with a pronounced reduction or absence of B-cells. Approximately 80 to 90% of individuals exhibit genetic variations in Bruton's agammaglobulinemia tyrosine kinase (BTK), whereas a minority of cases, around 5-10%, are autosomal recessive agammaglobulinemia (ARA). Very few cases are grouped into distinct subcategories. We evaluated phenotypically and genetically 27 patients from 13 distinct families with hypogammaglobinemia and no B-cells. Genetic analysis was performed via whole-exome and Sanger sequencing. The most prevalent genetic cause was mutations in BTK. Three novel mutations in the BTK gene include c.115 T > C (p. Tyr39His), c.685-686insTTAC (p.Asn229llefs5), and c.163delT (p.Ser55GlnfsTer2). Our three ARA patients include a novel homozygous stop-gain mutation in the immunoglobulin heavy constant Mu chain (IGHM) gene, a novel frameshift mutation of the B-cell antigen receptor complex-associated protein (CD79A) gene, a novel bi-allelic stop-gain mutation in the transcription factor 3 (TCF3) gene. Three patients with agammaglobulinemia have an autosomal dominant inheritance pattern, which includes a missense variant in PIK3CD, a novel missense variant in PIK3R1 and a homozygous silent mutation in the phosphoinositide-3-kinase regulatory subunit (RASGRP1) gene. This study broadens the genetic spectrum of hypogammaglobulinemia without B-cells and presented a few novel variants within the Iranian community, which may also have implications in other Middle Eastern populations. Notably, disease control was better in the second affected family member in families with multiple cases.

Association between serum IgG concentrations and the incidence of infections in patients with chronic lymphocytic leukemia and secondary immunodeficiency under treatment with Privigen.

OBJECTIVE: To investigate the association between serum immunoglobulin G (IgG) concentrations and the incidence of infections in patients with chronic lymphocytic leukemia (CLL) and secondary immunodeficiency receiving treatment with Privigen. MATERIALS AND METHODS: Data was analyzed from a non-interventional study conducted in 31 centers in Germany and 1 in Austria. Adult CLL patients with hypogammaglobulinemia and recurrent infections were allowed to enter the study upon signing informed consent, if a prior decision for treatment with Privigen had been made. All infections requiring an antimicrobial treatment were subject to analysis. Patients were stratified according to their mean post-baseline serum IgG trough levels in a group with lower IgG trough levels (≤ 5.0 g/L), and a group with higher IgG trough levels (> 5.0 g/L). RESULTS: Overall, 89 patients and 840 treatment cycles were analyzed. Up to 11 treatment cycles (average duration 29 days) were documented in each patient. In the group with higher IgG trough levels (> 5.0 g/L, N = 72), significantly fewer infections were observed than in the group with lower IgG trough levels (≤ 5.0 g/L, N = 17), including fewer severe and serious infections. The Privigen dosage was a major determinant of the post-baseline serum IgG levels. Overall tolerability of Privigen was assessed as very good or good in 91% of patients. CONCLUSION: This analysis confirms the association of serum IgG trough levels with the incidence of infections and highlights the importance of careful monitoring of IgG levels during treatment of secondary immunodeficiencies in CLL patients.