Common variable immunodeficiency and autoimmune diseases: A 10-year single-center experience.

Low percentages of regulatory T cells in common variable immunodeficiency (CVID) patients with autoimmune diseases and its association with increased numbers of CD4+CD45RO+ T and CD21low B cells

Common variable immunodeficiency (CVID) is the most common symptomatic inborn error of immunity in the world. While the autoimmune and end-organ lympho-infiltrative complications that occur in patients with CVID continue to drive high morbidity and mortality, we lack available FDA-approved therapeutics to treat these noninfectious CVID-related complications. Previously, we used unbiased network clustering of noninfectious autoimmune and end-organ lympho-infiltrative complications to define a high-risk CVID patient endotype. Here, we asked whether this high-risk CVID patient endotype overlaps with the clinical spectrum of activated PI3K-delta syndrome (APDS), a rare inborn error of immunity that can clinically present as CVID and has an existing FDA-approved immunomodulator for disease management. Data including patient demographics, ICD-10 coded immunodeficiency diagnoses, ICD-10 coded noninfectious disease complications, and detailed immunophenotype were extracted from existing registry and research databases of 983 patients with predominantly antibody deficiency (PAD), which included 423 patients with CVID, and compared with 46 patients with APDS. Unbiased network clustering of noninfectious disease complications alone was sufficient to cluster APDS patients with high-risk CVID and PAD patient cohorts. Specifically, APDS patients clustered tightly with CVID patients with clinical evidence of splenomegaly, lymphadenopathy, autoimmune cytopenias, interstitial lung disease, liver disease, and gut lumen disease resembling celiac disease. Using the criterion of two or more autoimmune and end-organ lympho-infiltrative complications, we identified that 74% (N = 314) of CVID patients and 28% (N = 274) of PAD patients exhibited an ‘APDS-like’ phenotype. Future directions include overlapping patient immunophenotypes to determine how this impacts clinical clustering. Together, these data demonstrate that a significant proportion of CVID patients assessed at major tertiary care centers exhibit a spectrum of noninfectious autoimmune and end-organ lympho-infiltrative disease that closely resembles those observed in APDS and suggest a possible shared pathophysiology which may have therapeutic implications.

Dose and outcomes in primary immunodeficiency disorders.

Comparison of clinical and immunological features and mortality in common variable immunodeficiency and agammaglobulinemia patients

Common variable immunodeficiency (CVID) and immunoglobulin (Ig) G subclass deficiency (IgGSD) are heterogeneous disorders characterized by respiratory tract infections, selective Ig isotype deficiencies, and impaired antibody responses to polysaccharide antigens. Using univariable analyses, we compared observations in 34 CVID and 398 IgGSD adult index patients (81.9% women) referred to a hematology/oncology practice. Similarities included specialties of referring physicians, mean ages, proportions of women, reactivity to Pneumovax, median serum IgG3 and IgG4 levels, median blood CD56+/CD16+ lymphocyte levels, positivity for HLA-A and -B types, and frequencies of selected HLA-A, -B haplotypes. Dissimilarities included greater prevalence of autoimmune conditions, lower median IgG, IgA, and IgM, and lower median CD19+, CD3+/CD4+, and CD3+/CD8+ blood lymphocytes in CVID patients. Prevalence of Sjögren's syndrome and hypothyroidism was significantly greater in CVID patients. Combined subnormal IgG1/IgG3 occurred in 59% and 29% of CVID and IgGSD patients, respectively. Isolated subnormal IgG3 occurred in 121 IgGSD patients (88% women). Logistic regression on CVID (versus IgGSD) revealed a significant positive association with autoimmune conditions and significant negative associations with IgG1, IgG3, and IgA and CD56+/CD16+ lymphocyte levels, but the odds ratio was increased for autoimmune conditions alone (6.9 (95% CI 1.3, 35.5)).

Rationale Interstitial (diffuse) lung disease (ILD) in common variable immunodeficiency (CVID) patients significantly impacts their quality of life and survival. We aimed to identify phenotypic characteristics associated with ILD in a large U.S. cohort of CVID patients. Methods We conducted a cross-sectional analysis of 1,470 CVID cases in the USIDNET registry. The primary outcome was physician-diagnosed ILD. Clinical characteristics were compared using chi-square or Wilcoxon–Mann–Whitney tests. Logistic regression evaluated associations between respiratory comorbidities, immunological features, extrapulmonary autoimmunity, and ILD. Results There were 103 CVID patients with known ILD (7%). Their median age was 47 years (IQR 25) compared with 50 years (IQR 38) in the non-ILD group, with a similar sex distribution, predominantly female (62.1% vs. 61%). Most ILD patients were asymptomatic for chronic respiratory symptoms, but dyspnea (15.5% vs. 3.6%, p < 0.001) and weight loss (14.6% vs. 7.1%, p = 0.007) were the most frequent symptoms. ILD patients had lower serum IgA levels (7 mg/dL vs. 29 mg/dL, p < 0.001) and CD3+, CD4+, CD8+, and CD19+ lymphocyte counts (p < 0.01). Chronic respiratory comorbidities associated with ILD included lung granulomas/multiple nodules (OR 16.75, 95% CI 9.23-30.39, p < 0.0001) and bronchiectasis (OR 3.1, 95% CI 1.9-5.1, p < 0.0001) independent of age. In contrast, upper airway inflammatory conditions and lower airway diseases (e.g., asthma and COPD) were not significantly associated. CVID patients with extrapulmonary immune dysregulation, including hepatosplenomegaly (OR 6.29, 95% CI 4.16-9.51, p < 0.0001), cytopenias (OR 3.9, 95% CI 2.59-5.88, p < 0.0001), inflammatory GI disease (OR 1.76, 95% CI 1.18-2.65, p = 0.006), and autoimmune endocrine disorders (OR 1.69, 95% CI 1.06-2.69, p = 0.028) also had an increased likelihood of ILD. No significant associations were observed between ILD and autoimmune skin or rheumatologic diseases. Conclusions CVID patients with ILD feature a severe phenotype characterized by a higher frequency of bronchiectasis, lung granulomas/nodules, reduced IgA, and T and B cells, as well as non-pulmonary immune dysregulation, particularly hematologic, GI, and endocrine manifestations. These findings highlight the need for targeted monitoring of lung disease in patients with these complications. Despite limitations (risk of recall/selection/attrition bias), our study provides valuable clinical insights into ILD in CVID patients and motivates further research into this highly relevant clinical problem.

B lymphocyte subpopulations, previously defined classification schemes (Freiburg, Paris, EuroClass), TNFRSF13B (TACI), TNFRSF13C (BAFF-R), TNFSF13 (APRIL) gene mutations, CTLA-4 and ICOS gene polymorphisms were analyzed in 25 common variable immunodeficiency (CVID) patients and 25 healthy controls. Patients were also divided into two subgroups due to some disease severity criteria. SG (severe disease group) (n:11) included patients who have splenomegaly and/or granulomatous diseases and/or bronchiectasis and/or lower baseline IgG values (<270 mg/dl). MG (moderate disease group) (n:14) patients diagnosed as having ESID/PAGID criteria but does not fulfill SG inclusion criteria. The onset of infectious symptoms and age at diagnosis were 50.0 ± 45.7 and 78.5 ± 54.5 months, respectively. Parental consanguinity rate was 54.5% in SG and 7.1% in MG. Switched-memory B cells (CD19 + 27 + IgD-IgM-) showed significant decrease in CVID patients and these cells were also significantly lower in SG compared to MG. CVID patients had significantly higher percentages of CD19 + κ + B cells and CD19 + λ + B cells than healthy controls. Freiburg classification: 87.5% of patients (n:21) were in group I and 12.5% were in Group II. Eighteen (75%) CVID patients with a low percentage of CD21(low) B cells were in Group Ib while three patients classified as Group Ia. The significantly lower levels of IgG and IgA in Group Ia is a novel finding. The percentages of patients for Paris Classification groups MB0, MB1, MB2 were 88%, 4% and 8%, respectively. There was a significant increase of splenomegaly, lymphadenopathy and autoimmune cytopenia in Group MB0. EuroClass: 45.8% of patients were smB+ and 54.2% were smB-. Splenomegaly and lymphadenopathy were significantly higher in smB- group. TACI: One patient carried heterozygous C104R mutation which was known as disease causing. APRIL: G67R and N96S SNPs were detected in most of the patients and healthy controls. BAFF-R: P21R/H159Y compound heterozygous mutation (n:1) and P21R heterozygous mutations (n:3) were detected. +49 A > G changes in exon 1 of CTLA-4 gene: GG and AG genotypes increase the risk of CVID development 1.32 and 2.18 fold, respectively. 1564 T > C polymorphisms on 3'UTR region in exon 2 of ICOS gene was not found to be significantly different in CVID patients. CVID classifications were not helpful in determining the genetic etiology of CVID.

Introduction: Common variable immunodeficiency (CVID) is characterized by recurrent infections, autoimmunity, lymphoproliferation, hypogammaglobulinemia, and defective antibody production. In CVID, B-cell abnormalities were described to predict end organ involvement and prognosis. Pediatric-onset CVID is much rarer than adult CVID, and lymphocyte subset abnormalities have not been thoroughly evaluated. Objective: We sought to determine lymphocyte subset abnormalities and their association with end organ involvement in pediatric-onset CVID patients. Methods: The clinical manifestations and laboratory findings including absolute numbers and percentages of B-, T-, and NK cell populations were assessed in pediatric-onset CVID patients and compared to age-matched healthy controls. The patients were divided into 2 groups according to age at assessment (pediatric CVID patients: 10–16 years, n = 9; and adult CVID patients: >16 years, n = 13). The comparisons between lymphocyte subsets and organ involvement were also evaluated. Results: Mean age at symptom onset was 18 (3–204) months. All CVID patients with pediatric onset had decreased levels of total and memory B cells, CD4⁺ T cells, CD4⁺CD45RA⁺ naive T cells, and recent thymic emigrant (RTE) cells. On the other hand, they had increases in CD8⁺CD45RO⁺ memory T cells. Interestingly, adult CVID patients demonstrated high frequencies of activated and double-negative T cells, which were unique only for this group of patients. Specific cellular abnormalities associated with the reduction in B and NK cells and increase in CD8⁺ T cells were found in patients with bronchiectasis. Moreover, in pediatric CVID patients, low serum IgA levels and decreased numbers of naive T and RTE cells were determined as risk factors for chronic diarrhea. Conclusions: Specific abnormalities in B- and T-lymphocyte compartments were identified in pediatric-onset CVID patients and appear to be associated with end organ manifestations.

Background. Common variable immunodeficiency (CVID) is the most frequent clinically symptomatic primary immunodeficiency; its clinical spectrum is highly variable, ranging from isolated recurrent infections to autoimmune (AID) and inflammatory rheumatic diseases (IRD), which may even be the unique manifestation at disease onset [1]. CVID is mainly a polygenic disease, even if recent studies employing whole-genome and exome sequencing analysis have highlighted that 15–30% may display a monogenic origin [2]. Aim of the study is to describe our CVID patients (pts) cohort, highlighting AID and IRD, and to describe genetic variants possibly linked to immunodeficiency and autoimmunity and therapeutic implications. Methods. This is a monocentric observational retrospective study considering CVID pts followed since 1985 to 2024. Diagnosis was made according to European Society for Immunodeficiency criteria [3]. A next generation sequencing (NGS) analysis of genes potentially linked to hypo-agammaglobulinemia and to antibody deficiency was executed when considered clinically appropriate. Results. Eighty-three pts with a CVID diagnosis were included. CVID total cohort description and comparisons between CVID pts with and without AID are reported in Table 1. Autoimmune cytopenia was the most common autoimmune manifestation occurring in 22.9% of the pts, with immune thrombocytopenia being the most prevalent. Immunosuppressive treatment was necessary in 89.5% of the pts affected by autoimmune cytopenia; in 5 cases, due to refractory cytopenia, rituximab was employed, achieving persistent remission in 4 pts. A diagnosis of IRD was made in 12 pts; 75.0% suffered from inflammatory arthritis. In one pt with Adenosine Deaminase 2 deficiency, genetic analysis aided in employing a target therapy leading remission of the IRD (Table 2). Genetic analysis for variants potentially leading to CVID had been performed in 37.3% of pts; analysis resulted positive in 41.9% of the tested. Genetic variants potentially linked to inborn errors of immunity (IEI) were found in more than half of pts with AID, much more frequently than in other CVID pts (56.5% vs 0.0%; p:0.010). The identified genetic variants are reported in Table 3. Conclusions CVID can be complicated by a wide spectrum of clinical pictures, including AID and IRD, being in our cohort inflammatory arthritis in most of the cases, categorized as a form of Spondyloarthritis in about two thirds. Notably, CVID pts affected by AID and IRD showed a higher frequency of genetic variants potentially leading to IEI; in one case genetic testing aided in orienting IS treatment, leading to remission of the IRD. Nowadays genetic analysis has still limited implications in influencing treatments in CVID, but in the future it might help in targeting precise mechanisms in patients with AID and IRD.

Common variable immunodeficiency (CVID) is a clinically and molecularly heterogeneous disorder with a varied clinical presentation 1. The age of onset varies from early childhood to much later in life, and the disease is characterized by recurrent bacterial infections, hypogammaglobulinaemia and impaired antibody responses. In addition to recurrent infections, which can be mild or serious, CVID patients often develop inflammatory and autoimmune disorders, malignancies and systemic granuloma formation, as well as gastrointestinal (GI) problems 2. Most CVID cases are sporadic, but there are also families with more than one affected member. A small proportion of patients with CVID present in patterns resembling autosomal recessive or dominant inheritance, and mutations in several genes involved directly or indirectly in B cell differentiation, have been identified. This small subset of CVID patients have defects in inducible co-stimulator (ICOS), CD19, CD20, CD21, CD81, lipopolysaccharide-responsive beige-like anchor (LRBA), B cell-activating factor (BAFF) receptor and CXCR4 [the latter causing WHIM (warts, hypogammaglobulinaemia, infections and myelokathexis) syndrome] 3. Additionally, two autosomal dominant defects affecting the genes for NFκB2 and PIK3CD have been described recently. The NFκB2 mutation causes haploinsufficiency and results in a CVID-like phenotype with childhood onset, autoimmune features and adrenal insufficiency 4. Nuclear factor kappa B2 (NF-κB2) is the principal downstream effector in the non-canonical NF-κB pathway and is required for appropriate B cell development. Dominant gain-of-function mutations in the PIK3CD gene encoding the catalytic P110δ and the p85α subunits of phosphoinositide 3-kinase (PI3 kinase) causes hyperactive PI3 kinase signalling, leading to early-onset autoimmunity, recurrent viral infections and bronchiectasis 5, 6. This suggests that clinical trials with PI3 kinase inhibitors are warranted. Most recently, a CVID-like syndrome, characterized by hypogammaglobulinaemia, a progressive loss of circulating B cells, immune dysregulation and lymphocytic infiltration of the brain, lung and gut was recognized to be caused by heterozygous mutations in the CTLA4 gene 7. CVID patients can be divided into those who exclusively experience infections (bacterial, viral or opportunistic) and, as a result, often develop chronic lung disease, and a second group who in addition develop an inflammatory condition. In the former subset, where recurrent infections are the primary symptom of concern, affected patients will have a near-normal life expectancy provided that they receive adequate treatment with intravenous immunoglobulin (IVIg) and/or antibiotics. Patients in the inflammatory subset are extremely prone to develop granulomas, autoimmune conditions and malignancies. Granulomas can develop in multiple locations, including the skin, lungs, liver and gut. Autoimmune conditions such as colitis, cytopaenia, hepatitis and malignancies, including leukaemia, lymphoma and colon cancer, are relatively frequent 1. This subset will generally have a reduced life expectancy and lower quality of life. Additionally, there is a third group encompassing conditions which are not considered 'classic' CVID: these are defects in T cell development, resulting in a 'CVID-like' condition with early-onset bronchiectasis, autoimmune disease and recurrent viral infections. These conditions (examples are LRBA deficiency 8 and gain-of-function mutations in the P110δ and the p85α subunits of PI3 kinase 5, 6) remain a diagnostic challenge, as it is unclear whether patients are suffering from 'true' CVID or a different type of hypogammaglobulinaemia with secondary B cell deficiency 9. Because both the genetics and clinical presentation of CVID are so variable, clinical diagnosis usually occurs by a lengthy process of eliminating other disorders. B cell phenotyping, T cell function assays, antigen (including neo-antigen) challenges, lymphokine studies, functional testing to measure processes such as phosphorylation of proteins, flow-based assays for surface and intracellular antigens, enzyme-linked immunosorbent assay (ELISA) and measurement of antibody production following vaccination with conjugate (Hib and Prevnar) and unconjugated (Pneumovax) vaccines are required to rule out other primary immunodeficiencies (PIDs). Because, in most cases, CVID may not be due to a single gene defect, molecular approaches thus far have been largely unrewarding, and successful in only a minority of CVID patients in identifying a genetic cause. Patients with a CVID-like phenotype and low numbers of circulating B cells may have mutations in the BTK gene, the cause of X-linked agammaglobulinaemia (XLA) or in genes causing autosomal recessive agammaglobulinaemia, including λ5, Igα, Igβ, B cell linker protein (BLINK) and γH 10. Recently, a homozygous mutation in the p85α subunit of PI3 kinase and a dominant negative mutation in E47 were found to cause agammaglobulinaemia 11, 12. The complexity of the molecular basis of CVID and the heterogeneity of the clinical phenotype requires a carefully designed treatment plan. The primary therapy is infusion of immunoglobulin, which can be either intravenous or subcutaneous, and is dosed based on the patient's immunoglobulin trough levels and clinical response, including frequency of infections. Prophylactic antibiotics help to prevent the development of chronic lung disease and immunosuppressive therapy of autoimmune complications are needed in some patients. Occasionally haematopoietic stem cell transplantation is required. As new causative genetic mutations are identified, new possibilities of gene defect-specific interventions become available. Promising results have been reported from recent studies using rituximab and azathioprine for the treatment of granulomatous lymphocytic interstitial lung disease associated with CVID 13. In terms of future directions for research into CVID, a key priority is to establish a more comprehensive set of diagnostic criteria for the differentiation of CVID and the less well-defined CVID-like conditions summarized here. Identification of novel CVID biomarkers will help to achieve this goal. Additional work in isolating causative genetic variants by whole exome/genome sequencing provides new opportunities to assist in genetic counselling and more specific therapies. Finally, research into better management of difficult-to-treat CVID symptoms such as subclinical infections, inflammatory complications and GI problems should be undertaken. The author would like to thank Meridian HealthComms Ltd for providing medical writing services. H. D. O. has received consultancy fees from CSL Behring.

Common variable immunodeficiency (CVID) is the most common, clinically relevant, primary immunodeficiency (PID). In the western world the incidence of this disease is about 1:50000. CVID is characterized by hypogammaglobulinemia which involves in all cases immunoglobulin G (IgG), in about 70-80% of cases immunoglobulin A (IgA) and in about 50% of cases immunoglobulin M (IgM). Additionally, patients with CVID develop weak or no immunization responses against polysaccharide (mainly) and protein antigens. Clinical manifestations of CVID may present either early in childhood or late in adulthood, usually between the third and fourth decade of life. The range of CVID clinical manifestations is broad. Underlying CVID should be considered mainly in cases of patients who present with recurrent or persistent bacterial infections of the upper or lower respiratory tract. The possibility of underlying CVID has also to be examined during laboratory investigation of various clinical syndromes, such as lymphadenopathy, hepatosplenomegaly, chronic diarrhea, or malabsorption, and also of autoimmune cytopenias such as idiopathic thrombocytopenic purpura and autoimmune hemolytic anemia. It is noteworthy, that autoimmune diseases and malignancies in the form of lymphoma and neoplasm of the gastrointestinal tract occur with increased incidence in CVID patients in comparison to the general population. Treatment strategy of CVID patients should not be limited to immunoglobulin substitution therapy (administered either intravenously or subcutaneously), but it also has to target effective management of infections and early diagnosis of occurring malignancies (lymphomas and gastrointestinal tumors) through systematic patient monitoring. With regard to life expectancy of CVID patients, two recently published large retrospective studies showed that CVID patients suffering only from infections had prolonged overall survival compared to those who presented with other CVID clinical manifestations. Exclusion of all potential causes of secondary hypogammaglobulinemia is mandatory for establishing the diagnosis of CVID. Also, in some CVID cases, differential diagnosis from other PID may be required, such as X-linked agammaglobulinemia (XLA), antibody deficiency with increased IgM (Hyper-IgM syndrome), and X-linked lymphoproliferative syndrome (XLP).

Background: Autoimmune diseases can occur at any time in patients with common variable immunodeficiency (CVID). However, the relationship between low immunoglobulin E (IgE) levels and autoimmune diseases in patients with CVID remains poorly understood. Objective: We aimed to determine the relationship between autoimmunity and low IgE in patients with CVID. Methods: This retrospective cohort study was conducted by using data that had been collected from 62 adult patients with CVID between April 2012 and December 2021. Serum basal IgE levels were compared between patients with and patients without autoimmune disease. Results: Overall, 23 of the 62 patients with CVID (37.1%) had at least one autoimmune disease (CVID-O). Autoimmune cytopenias, mainly immune thrombocytopenic purpura, were observed in half of all the patients. Other autoimmune diseases present among the patients included rheumatological diseases, inflammatory bowel diseases, lymphoma, granulomatous lymphocytic interstitial lung disease, autoimmune hepatitis, alopecia, and multiple sclerosis. Serum IgE levels were measured at the time of diagnosis; IgE was undetectable (<2.5 IU/mL) in 82.6% of the patients with CVID-O (n = 19). The median (interquartile range) serum IgE value in the patients with CVID-O was 2 IU/mL (1-16 IU/mL), which was significantly lower than the median serum IgE value in patients with CVID and without autoimmune disease (p < 0.001). Low IgE levels in patients with CVID-O were an independent risk factor for the development of autoimmune disease in patients with CVID (odds ratio 3.081 [95% confidence interval, 1.222-7.771]; p = 0.017). Conclusion: Low serum IgE levels were associated with the development of autoimmune disease in patients with CVID. The monitoring of serum IgE levels in patients with CVID may be useful in the early diagnosis and treatment of autoimmune diseases.

Common variable immunodeficiency (CVID) is the most common clinically significant primary immunodeficiency in adulthood, which presents a broad spectrum of clinical manifestations, often including non-infectious complications in addition to heightened susceptibility to infections. These protean manifestations may significantly complicate the differential diagnosis resulting in diagnostic delay and under-treatment with increased mortality and morbidity. Autoimmunity occurs in up to 30% of CVID patients, and it is an emerging cause of morbidity and mortality in this type of patients. 95 patients (42 males and 53 females) diagnosed with CVID, basing on ESID diagnostic criteria, were enrolled in this retrospective cohort study. Clinical phenotypes were established according to Chapel 2012: i) no other disease-related complications, ii) cytopenias (thrombocytopenia/autoimmune hemolytic anemia/neutropenia), iii) polyclonal lymphoproliferation (granuloma/lymphoid interstitial pneumonitis/persistent unexplained lymphadenopathy), and iv) unexplained persistent enteropathy. Clinical items in the analysis were age, gender, and clinical features. Laboratory data included immunoglobulin (Ig)G, IgM and IgA levels at diagnosis, flow-cytometric analysis of peripheral lymphocytes (CD3+, CD3+CD4+, CD3+CD8+, CD19+, CD4+CD25highCD127low, CD19hiCD21loCD38lo, and follicular T helper cell counts). Comparisons of continuous variables between groups were performed with unpaired t-test, when applicable. 39 patients (41%) showed autoimmune complications. Among them, there were 21 females (53.8%) and 18 males (46.2%). The most prevalent autoimmune manifestations were cytopenias (17.8%), followed by arthritis (11.5%), psoriasis (9.4%), and vitiligo (6.3%). The most common cytopenia was immune thrombocytopenia, reported in 10 out of 95 patients (10.5%), followed by autoimmune hemolytic anemia (n=3, 3.1%) and autoimmune neutropenia (n=3, 3.1%). Other autoimmune complications included thyroiditis, coeliac disease, erythema nodosum, Raynaud’s phenomenon, alopecia, recurring oral ulcers, autoimmune gastritis, and primary biliary cholangitis. There were no statistically significant differences comparing immunoglobulin levels between CVID patients with or without autoimmune manifestations. There was no statistical difference in CD3+, CD8+, CD4+CD25highCD127low T, CD19, CD19hiCD21loCD38lo, and follicular T helper cell counts in CVID patients with or without autoimmune disorders. In conclusion, autoimmune manifestations often affect patients with CVID. Early recognition and tailored treatment of these conditions are pivotal to ensure a better quality of life and the reduction of CVID associated complications.

Introduction: Regulatory lymphocytes (CD4+ T regulatory cells [Treg], CD8+ Treg, and B regulatory cells [Breg]) play a critical role in immune homeostasis and tolerance. Common variable immunodeficiency (CVID) is associated with increased susceptibility to infections and increased frequency of inflammatory and autoimmune diseases. CD4+ Treg cell abnormalities have been reported in CVID; however, CD8+ Treg cells have not been reported in CVID. The objective of this study was to evaluate CD4+ Treg and CD8+ Treg cells in CVID patients. Methods: In 25 patients with CVID and age-matched healthy controls, Treg cells, evaluated in freshly isolated peripheral blood mononuclear cells (natural; nCD4+ Treg and nCD8+ Treg) and following in vitro activation with anti-CD3/CD28 monoclonal antibodies (induced; iCD4+ Treg and iCD8+ Treg) as well as Breg cells were analyzed with specific monoclonal antibodies and isotype controls using flow cytometry. Results: The proportions of nCD4+ Treg (CD4+ CD127^low CD25^high FoxP3+), iCD4+ Treg (CD4+ CD127^low CD25^high FoxP3+), iCD8+ Treg (CD8+ CD25^high CD183+ FoxP3+), and Breg (CD19+ CD24^high CD38^high) lymphocytes were significantly lower in patients with CVID than in controls. Conclusions: Altered regulatory lymphocytes may play a role in the pathogenesis and autoimmunity and inflammation associated with CVID.

Common variable immunodeficiency (CVID) comprises a heterogeneous group of primary immunodeficiency disorders. Immunophenotyping of memory B cells at the time of diagnosis is increasingly used for the classification of patients into subgroups with different clinical prognoses. The EUROclass classification is a widely used method. Levels of somatic hypermutation (SHM) have proven useful as a prognostic marker for recurrent respiratory tract infections. As time of presentation and diagnosis is highly variable in CVID patients, and diagnostic delay is a common problem, it is important to know whether classification parameters are stable over time. The purpose of the study was to address this question in a cohort of 33 CVID patients followed from 3 to 19 years after diagnosis (average follow-up 8.8 years). Levels of class-switched memory B cells were analyzed using flow cytometric immunophenotyping, and patients were classified according to the EUROclass criteria. Affinity maturation of B cells was measured using Igκ-REHMA, which assesses somatic hypermutation in kappa light chain transcripts. Clinical manifestations in terms of splenomegaly, autoimmune disease and granulomatous disease were also determined. Switched memory B cells and levels of SHM were not consistently stable markers in a long-term follow-up setting. At a given time during follow-up, 60% of the patients were assigned to the EUROclass group SmB- (less than 2% switched memory B cells), but only 23% were consistently assigned to this group. Associations between clinical manifestations and levels of switched memory B cells or SHM were not observed in our study. Based on our findings, we suggest that immunologic characteristics in CVID patients should be evaluated several times after diagnosis using internationally standardized methods.