Common variable immunodeficiency: the immune system in chaos

Immunological biomarkers associated with survival in a cohort of Argentinian patients with common variable immunodeficiency

Background

Common variable immunodeficiency (CVID) is the most common symptomatic syndrome among inborn errors of immunity. Although several aspects of CVID immunopathology have been elucidated, predictive factors for mortality are incompletely defined. A genetic cause can be identified only in approximately 30% of patients.

Objective

We sought to develop a mortality predictive score on the basis of the immunophenotypes and genotypes of patients with CVID.

Methods

Twenty-one patients diagnosed with CVID in Córdoba, Argentina, were analyzed for clinical and laboratory data. Immunophenotyping was done by flow cytometry. CVID-associated mutations were identified by whole-exome sequencing.

Results

Alive (15) and deceased (6) patients were compared. Univariate analysis showed significant differences in CD4+ T cells (P = .002), natural killer (NK) cells (P = .001), and memory switched B cells (P = .001) between groups. Logistic regression analysis showed a negative correlation between CD4+, NK, and memory switched B-cell counts and probability of survival over a 10-year period (CD4+ T cells: odds ratio [OR], 1.01; 95% CI, 1.001-1.020; NK cells: OR, 1.07; 95% CI, 1.02-1.17; and memory switched B cells: OR, 26.23; 95% CI, 2.06-2651.96). Receiver-operating characteristic curve analysis identified a survival cutoff point for each parameter (CD4+ T cells: 546 cells/mL; AUC, 0.87; sensitivity, 60%; specificity, 100%; memory switched B cells: 0.84 cells/mL; AUC, 0.92; sensitivity, 100%; specificity, 85%; and NK cells: 45 cells/mL; AUC, 0.92; sensitivity, 83%; specificity, 100%). Genetic analysis on 14 (9 female and 5 male) patients from the cohort revealed mutations associated with inborn errors of immunity in 6 patients.

Conclusions

A score to predict mortality is proposed on the basis of CD4+ T, NK, and memory switched B-cell counts in patients with CVID.

Comparison of Post-Vaccination Cellular Immune Response in Patients with Common Variable Immune Deficiency

BACKGROUND

The problem of identifying vaccine-specific T-cell responses is still a matter of debate. Currently, there are no universal, clearly defined, agreed upon criteria for assessing the effectiveness of vaccinations and their immunogenicity for the cellular component of immunity, even for healthy people. But for patients with inborn errors of immunity (IEI), especially those with antibody deficiencies, evaluating cellular immunity holds significant importance.

AIM

To examine the effect of one and two doses of inactivated adjuvanted subunit influenza vaccines on the expression of endosomal Toll-like receptors (TLRs) on the immune cells and the primary lymphocyte subpopulations in patients with common variable immunodeficiency (CVID).

MATERIALS AND METHODS

During 2018-2019, six CVID patients received one dose of a quadrivalent adjuvanted influenza vaccine; in 2019-2020, nine patients were vaccinated with two doses of a trivalent inactivated influenza vaccine. The proportion of key lymphocyte subpopulations and expression levels of TLRs were analyzed using flow cytometry with monoclonal antibodies.

RESULTS

No statistically significant alterations in the absolute values of the main lymphocyte subpopulations were observed in CVID patients before or after vaccination with the different immunization protocols. However, after vaccination, a higher expression of TLR3 and TLR9 in granulocytes, monocytes, and lymphocytes was found in those patients who received two vaccine doses rather than one single dose.

CONCLUSION

This study marks the first instance of using a simultaneous two-dose vaccination, which is associated with an elevated level of TLR expression in the immune cells. Administration of the adjuvanted vaccines in CVID patients appears promising. Further research into their impact on innate immunity and the development of more effective vaccination regimens is warranted.

Studying the cellular basis of small bowel enteropathy using high-parameter flow cytometry in mouse models of primary antibody deficiency

Background

Primary immunodeficiencies are heritable defects in immune system function. Antibody deficiency is the most common form of primary immunodeficiency in humans, can be caused by abnormalities in both the development and activation of B cells, and may result from B-cell-intrinsic defects or defective responses by other cells relevant to humoral immunity. Inflammatory gastrointestinal complications are commonly observed in antibody-deficient patients, but the underlying immune mechanisms driving this are largely undefined.

Methods

In this study, several mouse strains reflecting a spectrum of primary antibody deficiency (IgA-/-, Aicda-/-, CD19-/- and JH -/-) were used to generate a functional small-bowel-specific cellular atlas using a novel high-parameter flow cytometry approach that allows for the enumeration of 59 unique cell subsets. Using this cellular atlas, we generated a direct and quantifiable estimate of immune dysregulation. This estimate was then used to identify specific immune factors most predictive of the severity of inflammatory disease of the small bowel (small bowel enteropathy).

Results

Results from our experiments indicate that the severity of primary antibody deficiency positively correlates with the degree of immune dysregulation that can be expected to develop in an individual. In the SI of mice, immune dysregulation is primarily explained by defective homeostatic responses in T cell and invariant natural killer-like T (iNKT) cell subsets. These defects are strongly correlated with abnormalities in the balance between protein (MHCII-mediated) versus lipid (CD1d-mediated) antigen presentation by intestinal epithelial cells (IECs) and intestinal stem cells (ISCs), respectively.

Conclusions

Multivariate statistical approaches can be used to obtain quantifiable estimates of immune dysregulation based on high-parameter flow cytometry readouts of immune function. Using one such estimate, we reveal a previously unrecognized tradeoff between iNKT cell activation and type 1 immunity that underlies disease in the small bowel. The balance between protein/lipid antigen presentation by ISCs may play a crucial role in regulating this balance and thereby suppressing inflammatory disease in the small bowel.

Studying the cellular basis of small bowel enteropathy using high-parameter flow cytometry in mouse models of primary antibody deficiency

Background

Primary immunodeficiencies are heritable defects in immune system function. Antibody deficiency is the most common form of primary immunodeficiency in humans, can be caused by abnormalities in both the development and activation of B cells, and may result from B-cell-intrinsic defects or defective responses by other cells relevant to humoral immunity. Inflammatory gastrointestinal complications are commonly observed in antibody-deficient patients, but the underlying immune mechanisms driving this are largely undefined.

Methods

In this study, several mouse strains reflecting a spectrum of primary antibody deficiency (IgA -/- , Aicda -/- , CD19 -/- and J H -/- ) were used to generate a functional small-bowel-specific cellular atlas using a novel high-parameter flow cytometry approach that allows for the enumeration of 59 unique cell subsets. Using this cellular atlas, we generated a direct and quantifiable estimate of immune dysregulation. This estimate was then used to identify specific immune factors most predictive of the severity of inflammatory disease of the small bowel (small bowel enteropathy).

Results

Results from our experiments indicate that the severity of primary antibody deficiency positively correlates with the degree of immune dysregulation that can be expected to develop in an individual. In the SI of mice, immune dysregulation is primarily explained by defective homeostatic responses in T cell and invariant natural killer-like T (iNKT) cell subsets. These defects are strongly correlated with abnormalities in the balance between protein (MHCII-mediated) versus lipid (CD1d-mediated) antigen presentation by intestinal epithelial cells (IECs) and intestinal stem cells (ISCs), respectively.

Conclusions

Multivariate statistical approaches can be used to obtain quantifiable estimates of immune dysregulation based on high-parameter flow cytometry readouts of immune function. Using one such estimate, we reveal a previously unrecognized tradeoff between iNKT cell activation and type 1 immunity that underlies disease in the small bowel. The balance between protein/lipid antigen presentation by ISCs may play a crucial role in regulating this balance and thereby suppressing inflammatory disease in the small bowel.

Autoimmune disorders associated with common variable immunodeficiency: prediction, diagnosis, and treatment

INTRODUCTION

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency. Due to the wide spectrum of the CVID manifestations, the differential diagnosis becomes complicated, ends in a diagnostic delay and increased morbidity and mortality rates. Autoimmunity is one of the important complications associated with CVID. While immunoglobulin replacement therapy has considerably decreased the mortality rate in CVID patients, mainly infection-related mortality, other complications such as autoimmunity appeared prevalent and, in some cases, life threatening.

AREAS COVERED

In this article, genetics, responsible immune defects, autoimmune manifestations in different organs, and the diagnosis and treatment processes in CVID patients are reviewed, after searching the literature about these topics.

EXPERT OPINION

Considering the many phenotypes of CVID and the fact that it remained undiagnosed until older ages, it is important to include various manifestations of CVID in the differential diagnosis. Due to the different manifestations of CVID, including autoimmune diseases, interdisciplinary collaboration of physicians from different fields is highly recommended, as discussed in the manuscript. Meanwhile, it is important to determine which patients could benefit from genetic diagnostic studies since such studies are not necessary for establishing the diagnosis of CVID.

A case of progressive multifocal leukoencephalopathy with hypogammaglobulinemia and a TCF3 mutation

Progressive multifocal leukoencephalopathy (PML) is a rare and potentially fatal demyelinating disease of the central nervous system (CNS) caused by JC virus; it was previously seen predominantly in immunocompromised patients and those under intense immune suppression. Here, we report the case of a patient with PML with hypogammaglobulinemia and a heterozygous mutation in the TCF3 gene. As the TCF3 gene has been demonstrated to play an important role in the B cell differentiation process and the patient had no other medical history of the immune system, he was diagnosed with common variable immunodeficiency (CVID). To our knowledge, this is the first case of patient with a TCF3 gene deficiency and hypogammaglobulinemia who developed PML.

Gastrointestinal involvement of common variable immunodeficiency: A diagnostic challenge to the physician

A 35-year-old male presented with fatigue for 1 month and was found to have megaloblastic anaemia. Further evaluation showed low globulin levels and pan hypogammaglobulinemia. Past history was significant for chronic small bowel diarrhoea and bilateral genu valgum deformity from childhood. Hence, a malabsorption syndrome with a probable antibody deficiency was suspected. An upper gastrointestinal (GI) endoscopy was done, which revealed chronic atrophic gastritis with Helicobacter pylori infection, dysplasia and subtotal villous atrophy with a paucity of plasma cells, which was suggestive of common variable immunodeficiency (CVID)-related enteropathy. CVID can present with predominantly autoimmune GI manifestations without any history of recurrent infections. The risk of gastric dysplasia and malignancy is high in CVID and needs close monitoring.

Intra cranial granulomatous disease in common variable immunodeficiency: Case series and review of the literature

BACKGROUND/PURPOSE

Common variable immunodeficiency (CVID) is typically characterized by hypogammaglobulinemia and often but not always recurrent infections. Paradoxically, 8-22% of patients with CVID develop granulomatous disease. Granulomata have been described in many organs including the lungs, skin, liver, spleen, kidneys, eyes, lymph nodes, and intestines. Data about central nervous system (CNS) involvement in CVID are extremely rare. We aim to describe a case series and include an extensive literature review of CNS involvement in CVID to understand the different features and patterns of the disease.

METHODS

We searched the English Pubmed database for relevant articles between 1950 and 2014 using the Key Words "common variable immunodeficiency", "granulomatous disease", "brain", "sarcoidosis", and "sarcoid-like syndrome". Data from all case series, surveys, systematic reviews, and individual case reports, as well as retrospective studies were extracted. A total of 15 patients were reported in the literature. We combined our experience with four additional patients from The Cleveland Clinic between 2009 and 2014. Demographics, clinical features, laboratory and imaging findings, treatment and follow-up were extracted for the 19 patients and summarized descriptively.

RESULTS

Female sex and Caucasian race represented 63.2% (12/19), and 80% of the patients, respectively. The mean age of CVID diagnosis was 24 years; mean age when the CNS disease was diagnosed was 21.5 years. 68.4% of the patients (13/19) had granulomas involving ≥2 organs including the central nervous system, 31.6% (6/19) had CNS granulomas only. Associated granulomatous diseases occurred in lungs (72.7%), lymph nodes (27.2%), spleen (27.2%), eyes (18.1%), liver (18.1%), parotid glands (9%), and skin (9%). Fifty-three percent (10/19) of the patients had documented recurrent infections, all of them being upper respiratory tract infections. CNS manifestations included seizures (31.6%), headaches (21%), vision loss (15.7%), decreased cognition (10.5%), focal weakness (5.2%), nystagmus (5.2%), ataxia (5.2%), coma (5.2%), polyuria, and polydipsia (5.2%). Brain mass was the most common radiologic finding (70%) followed by leptomeningeal enhancement (10%), non-specific white matter lesions (10%) and absence of normal signal of the neurohypophysis (10%). Brain pathology was available in 12 patients: findings included granulomatous disease in 83.3%, angiocentric granulomas in 50%, vasculitis without granulomas in 8.3%, and lymphocytic infiltrate of the meninges with diffuse non-caseating granulomas in 8.3%. Cerebrospinal fluid analysis revealed elevated total proteins with/or without lymphocytic pleocytosis in 80%.

CONCLUSION

CNS disease is a rare challenging complication of CVID. Patients with brain involvement are generally female, Caucasian, and likely have lung involvement. Although immunoglobulin and steroids remain the first line of treatment, other immunosuppressive agents have shown some promise with regards to recurrent relapsing presentations.

Limited role of interferon-kappa (IFNK) truncating mutations in common variable immunodeficiency

We used whole exome sequencing to determine the genetic background of CVID in two non-consanguineous German families. We identified IFNK (interferon-kappa) as the only candidate gene that harbored truncating mutations in affected members from both families. One family segregated c.30_31insTGTT, a known frameshift variant, while the other family segregated the novel IFNK mutation p.K199X that creates a premature stop codon. We sequenced the whole coding region of IFNK in a further series of 167 CVID patients and 192 healthy controls. Frameshift mutation c.30_31insTGTT was identified in 12 cases and 17 controls (OR 0.79, 95% CI 0.33-1.81, p=0.79), whereas the p.K199X mutation remained restricted to the original family. No additional truncating variants were found. We conclude that, given their frequent occurrence in non-diseased family members and controls, it is unlikely that truncating variants in IFNK constitute a major factor in the development of CVID.

Chitotriosidase enzyme activity: is this a possible chronic inflammation marker in children with common variable immunodeficiency and early atherosclerosis?

Background Common variable immunodeficiency is a rare clinically symptomatic primary immunodeficiency disorder which manifests a wide variability of symptoms, complications. Atherosclerosis in common variable immunodeficiency patients has not been investigated yet contrary to other severe clinical complications. We aimed to investigate the chitotriosidase enzyme's role as an inflammation and atherosclerosis marker in paediatric common variable immunodeficiency patients. Methods Common variable immunodeficiency patients (n = 24) and healthy controls (n = 23) evaluated for chitotriosidase activity with other inflammation markers (hsCRP, myeloperoxidase, serum amyloid A, ferritin), lipid profile and echocardiographic findings (carotid artery intima media thickness - cIMT, brachial artery flow-mediated vazodilatation - FMD%). Results In patients, the mean chitotriosidase activity (8.98 ± 6.28) was significantly higher than the controls (5.17 ± 3.42) ( P = 0.014). Chitotriosidase showed positive relation with hs-CRP ( P = 0.011) and SAA ( P = 0.011) but had no relation with ferritin ( P = 0.155), HDL ( P = 0.152) or LDL-cholesterol ( P = 0.380). Mean cIMT increased in patients compared with the controls ( P < 0.001) but did not show any relation with chitotriosidase ( P = 0.546). FMD% decreased in patients ( P < 0.001) also showing no relation with chitotriosidase ( P = 0.298). Ventricular myocardial performance indexes had no significant difference, but RVEF% decreased in patients ( P = 0.043). Conclusions High chitotriosidase activity in common variable immunodeficiency patients demonstrated in vivo the presence of activated macrophages indicating ongoing inflammation. Echocardiographic diastolic functional deficiency, increased cIMT and decreased FMD% may be accepted as early atherosclerotic findings, but none of them showed relationship with chitotriosidase activities.

The role of toll-like receptors in B-cell development and immunopathogenesis of common variable immunodeficiency

Common variable immunodeficiency (CVID) is the most frequent symptomatic primary immune deficiency and is characterized by hypogammaglobulinemia, defect in specific antibody response and increased susceptibility to recurrent infections, malignancy and autoimmunity. Patients with CVID often have defects in post-antigenic B-cell differentiation, with fewer memory B cells and impaired isotype switching. Toll-like receptors (TLRs) are expressed on various immune cells as key elements of innate and adaptive immunity. TLR signaling in B cells plays multiple roles in cell differentiation and activation, class-switch recombination and cytokine and antibody production. Moreover, recent studies have shown functional alteration of TLRs responses in CVID patients including poor cell proliferation, impaired upregulation of co-stimulatory molecules and failure in cytokine and immunoglobulin production. The purpose of the present review is to discuss the role of TLRs in B-cell development and function as well as their role in the immunopathogenesis of CVID.

CD47 deficiency ameliorates autoimmune nephritis in Fas(lpr) mice by suppressing IgG autoantibody production

CD47, a self-recognition marker, plays an important role in both innate and adaptive immune responses. To explore the potential role of CD47 in activation of autoreactive T and B cells and the production of autoantibodies in autoimmune disease, especially systemic lupus erythematosus (SLE), we have generated CD47 knockout Fas(lpr) (CD47(-/-) -Fas(lpr) ) mice and examined histopathological changes in the kidneys, cumulative survival rates, proteinuria, extent of splenomegaly and autoantibodies, serum chemistry and immunological parameters. In comparison with Fas(lpr) mice, CD47(-/-) -Fas(lpr) mice exhibit a prolonged lifespan and delayed autoimmune nephritis, including glomerular cell proliferation, basement membrane thickening, acute tubular atrophy and vacuolization. CD47(-/-) -Fas(lpr) mice have lower levels of proteinuria, associated with reduced deposition of complement C3 and C1q, and IgG but not IgM in the glomeruli, compared to age-matched Fas(lpr) mice. Serum levels of antinuclear antibodies and anti-double-stranded DNA antibodies are significantly lower in CD47(-/-) -Fas(lpr) than in Fas(lpr) mice. CD47(-/-) -Fas(lpr) mice also display less pronounced splenomegaly than Fas(lpr) mice. The mechanistic studies further suggest that CD47 deficiency impairs the antigenic challenge-induced production of IgG but not IgM, and that this effect is associated with reduction of T follicular cells and impairment of germinal centre development in lymphoid tissues. In conclusion, our results demonstrate that CD47 deficiency ameliorates lupus nephritis in Fas(lpr) mice via suppression of IgG autoantibody production.

A Clinical and Laboratory Approach to the Evaluation of Innate Immunity in Pediatric CVID Patients

Defective adaptive immune responses are well studied in common variable immunodeficiency (CVID) patients; however, more focus is needed on innate immune system defects to explain CVID’s clinical and laboratory heterogeneity. This is the first study comparing migratory function of granulocytes, oxidative burst activity of phagocytic cells, surface integrin expressions on neutrophils and lymphocytes, natural killer (NK) cell numbers and cytotoxic activity, natural killer T cells, lymphocyte subsets such as CD8⁺CD28⁺, CD4⁺CTLA-4⁺ cells in CVID patients (n: 20) and healthy controls (n: 26). The relationship between laboratory findings and some clinical was also investigated. CD3⁺CD8⁺ T cytotoxic cells were found to be elevated in CVID patients, but CD3⁺CD8⁺CD28⁺ or CD3⁺CD8⁺CD28⁻ cells did not show any significant difference. CD4⁺CTLA-4⁺ cell percentages were significantly lower in CVID patients compared to healthy controls. Severe CVID patients had decreased percentages of NK cells with increased NK cell cytotoxicity suggesting possibly increased activation. Furthermore, CD3⁻CD16⁺CD56⁺CD28⁺ cells of CVID patients were elevated while percentage of CD28⁻ NK cells was decreased. Neutrophil migration percentages were lower but and oxidative burst activity was not affected. CD11a expressions on these cells were depressed in contrast to increased expression of CD18. Innate immunity defects may affect the extent of recurrence and severity of infections in CVID. Our observations highlight some of these associations and indicate the need for further similar studies for improving better innate system evaluation batteries for these patients. Further phenotypic correlations of these analyses will help clinicians reach a more definitive target for the molecular genetic diagnostic of pediatric CVID patients.

Fatal encephalitis due to BK virus in a patient with common variable immunodeficiency: a case report

Encephalitis due to BK virus is a rare condition. Here, we describe a young male patient with common variable immunodeficiency who developed fatal encephalitis due to BK virus. The patient presented initially with ocular symptoms that were followed by behavioral changes and spastic quadriparesis. Diagnosis was made by the compatible clinical findings and detection of viral DNA by polymerase chain reaction in the cerebrospinal fluid. To the best of our knowledge, this is the first report of BK virus encephalitis in a patient with common variable immunodeficiency. We suggest that BK virus should be suspected in cases of encephalitis; particularly in patients with immunodeficiency.

Liver transplantation for severe hepatitis in patients with common variable immunodeficiency

CVID is a heterogeneous group of primary immunodeficiency diseases characterized by hypogammaglobulinemia, recurrent bacterial infections, and frequent autoimmune manifestations. The post-transplant course of liver transplant recipients with CVID is rarely described. We report two patients with CVID complicated by severe enteropathy who underwent living donor liver transplantation for liver failure because of severe hepatitis. The post-transplant course was complicated by recurrent acute rejection, leading to ductopenic rejection in one and recurrent hepatitis in the other. We reviewed the tissue samples histologically and immunohistochemically. Native livers showed submassive hepatocyte necrosis in one and cirrhotic liver with active hepatitis in the other, both with infiltration of CD8+ T cells accompanied by endothelialitis and bile duct damage; the intestine contained increased numbers of intraepithelial CD8+ T cells with apoptosis of epithelial cells. The liver allograft exhibited acute rejection, with prominent CD8+ T cells infiltrating the bile duct or endothelium. In the allograft following the diagnosis of post-transplant recurrent hepatitis, CD8+ T cells comprised the majority of infiltrating cells in portal areas spilling over into hepatic parenchyma. Our cases suggest that T cells contribute to the pathogenesis of CVID in native organs as well as allografts and may constitute evidence of T-cell deregulation in the pathogenesis of CVID.

Intravenous immunoglobulins in immunodeficiencies: more than mere replacement therapy

Intravenous immunoglobulin (IVIG) is a therapeutic compound prepared from pools of plasma obtained from several thousand healthy blood donors. For more than 20 years, IVIG has been used in the treatment of a wide range of primary and secondary immunodeficiencies. IVIG now represents a standard therapeutic option for most antibody deficiencies. Routinely, IVIG is used in patients with X-linked agammaglobulinaemia (XLA), common variable immunodeficiency (CVID), X-linked hyper-IgM, severe combined immunodeficiency, Wiskott-Aldrich syndrome, and selective IgG class deficiency. In addition, IVIG is used extensively in the treatment of a wide variety of autoimmune disorders. IVIG is administered at distinct doses in the two clinical settings: whereas immunodeficient patients are treated with replacement levels of IVIG, patients with autoimmune and inflammatory diseases are administered with very high doses of IVIG. Several lines of experimental evidence gathered in the recent years suggest that the therapeutic beneficial effect of IVIG in immunodeficiencies reflects an active role for IVIG, rather than a mere passive transfer of antibodies.

Intravenous immunoglobulin induces proliferation and immunoglobulin synthesis from B cells of patients with common variable immunodeficiency: a mechanism underlying the beneficial effect of IVIg in primary immunodeficiencies

Common variable immunodeficiency (CVID) is associated with low serum immunoglobulin concentrations and an increased susceptibility to infections and autoimmune diseases. The treatment of choice for CVID patients is replacement intravenous immunoglobulin (IVIg) therapy. IVIg has been beneficial in preventing or alleviating the severity of infections and autoimmune and inflammatory process in majority of CVID patients. Although the mechanisms of action of IVIg given as 'therapeutic high dose' in patients with autoimmune diseases are well studied, the underlying mechanisms of beneficial effects of IVIg in primary immunodeficiencies are not completely understood. Therefore we investigated the effect of 'replacement dose' of IVIg by probing its action on B cells from CVID patients. We demonstrate that IVIg at low doses induces proliferation and immunoglobulin synthesis from B cells of CVID patients. Interestingly, B cell stimulation by IVIg is not associated with induction of B cell effector cytokine IFN-γ and of transcription factor T-bet. Together, our results indicate that in some CVID patients, IVIg rectifies the defective signaling of B cells normally provided by T cells and delivers T-independent signaling for B cells to proliferate. IVIg 'replacement therapy' in primary immunodeficiencies is therefore not a merepassive transfer of antibodies to prevent exclusively the recurrent infections; rather it has an active role in regulating autoimmune and inflammatory responses through modulating B cell functions and thus imposing dynamic equilibrium of the immune system.

Inflammatory bowel diseases in patients with adaptive and complement immunodeficiency disorders

Crohn's disease and ulcerative colitis are idiopathic chronic inflammatory diseases that primarily affect the gastrointestinal tract. The underlying causes remain poorly understood, but there is a growing body of evidence advocating a likely primary pathogenic role for immunodeficiency in the development of Crohn's lesions. Concordantly, a number of congenital immunodeficiencies disrupting the cellular innate immune system strongly predispose to noninfectious, Crohn's-like inflammatory bowel disease. There are case reports and series suggesting that the same may be true for some of the congenital adaptive and complement immunodeficiencies. This review considers and critiques these potential associations.

Altered spectrum of somatic hypermutation in common variable immunodeficiency disease characteristic of defective repair of mutations

Pathogenic common variable immunodeficiency diseases (CVID) are genetic, usually inherited diseases for which a limited number of genetic defects have been implicated. As CVID presents with a wide range of clinical characteristics, there are likely diverse and for the most part unidentified genetic causes. In some individuals, defects in somatic hypermutation (SHM) have been suggested as the underlying cause of CVID. To address the mechanisms of SHM defects in CVID, we conducted a comprehensive mutational analysis of immunoglobulin heavy chain sequences from CVID patients. We identified several remarkably specific alterations in the spectra of SHM in comparison to healthy individuals. We provide evidence that some CVID cases are associated with defective repair of AID-induced mutations by the DNA mismatch repair (MMR) machinery. Our findings together with reports of increased chromosomal radiosensitivity and associated lymphoproliferative disorders amongst CVID patients, suggest that altered DNA damage repair may be a cause of CVID.

Regulatory T cell dysfunction in subjects with common variable immunodeficiency complicated by autoimmune disease

Approximately 25% of subjects with common variable immunodeficiency (CVID) develop autoimmune disease. We analyzed T cell subsets, specifically regulatory T cells along with B cell subsets to determine whether there were changes in regulatory T cells which would correlate with the autoimmune disease clinical phenotype in CVID subjects. We hypothesized that regulatory T cell (CD4+CD25hiCD127lo) suppressive function would be impaired in CVID subjects with autoimmune disease. Using purified, sorted Treg from CVID subjects (n=14) and from healthy controls (HC, n=5) in standard suppression assays, we found the suppressive function of Treg from CVID subjects with autoimmune disease (CVID w/ AI, n=8) to be significantly attenuated compared to CVID subjects with no autoimmune disease (CVID w/o AI, n=6) and to HC (n=5). A number of proteins associated with Treg function were decreased in expression as detected through immunofluorescent antibody via flow cytometry (mean fluorescence intensity (MFI) of FoxP3, Granzyme A, XCL1, pSTAT5, and GITR in Treg was significantly lower (by up to 3 fold) in CVID w/ AI compared to CVID w/o AI and HC. Furthermore, a statistically significant correlation was found between intracellular MFI of FoxP3, Granzyme A, and pSTAT5 in Treg and the degree of Treg dysfunction. These results suggest that attenuation of Treg function is associated with autoimmune disease in CVID subjects and may contribute to autoimmune pathogenesis.

Modulation of the cellular immune system by intravenous immunoglobulin

Intravenous immunoglobulin (IVIg) is therapeutically used in a variety of immune-mediated diseases. The beneficial effects of IVIg in auto-antibody-mediated diseases can be explained by neutralization, accelerated clearance and prevention of Fcgamma-receptor binding of auto-antibodies. However, the means by which IVIg exerts therapeutic effects in disorders mediated by cellular immunity have remained enigmatic. Clinical improvements, followed by IVIg treatment, often extend beyond the half-life of infused IgG, thereby indicating that IVIg modifies the cellular immune compartment for a prolonged period. Here, we discuss recent advances in the understanding of different, mutually non-exclusive mechanisms of action of IVIg on cells of the innate and adaptive immune system. These mechanisms might explain the beneficial effects of IVIg in certain autoimmune and inflammatory diseases.

Sweet's syndrome in association with common variable immunodeficiency

Sweet's syndrome (SS), a rare reactive neutrophilic dermatosis, has been reported to occur in association with a variety of systemic disorders, categorized by von den Diesch into idiopathic, paraneoplastic, pregnancy and parainflammatory subgroups. The parainflammatory group has been well defined, and includes a wide spectrum of infectious triggers and disorders of immune dysregulation. To date, however, no cases of SS have been described in the context of common variable immunodeficiency (CVID). We report a case of paediatric-onset SS, previously reported as idiopathic, with a subsequent diagnosis of CVID.

Common variable immunodeficiency: a new look at an old disease

Primary immunodeficiencies comprise many diseases caused by genetic defects primarily affecting the immune system. About 150 such diseases have been identified with more than 120 associated genetic defects. Although primary immunodeficiencies are quite rare in incidence, the prevalence can range from one in 500 to one in 500 000 in the general population, depending on the diagnostic skills and medical resources available in different countries. Common variable immunodeficiency (CVID) is the primary immunodeficiency most commonly encountered in clinical practice, and appropriate diagnosis and management of patients will have a significant effect on morbidity and mortality as well as financial aspects of health care. Advances in diagnostic laboratory methods, including B-cell subset analysis and genetic testing, coupled with new insights into the molecular basis of immune dysfunction in some patients with CVID, have enabled advances in the clinical classification of this heterogeneous disease.

Autoimmunity in common variable immunodeficiency

BACKGROUND

Autoimmunity has been increasingly recognized as a major issue in patients with common variable immunodeficiency (CVID), the most common symptomatic primary immunodeficiency in adulthood. Different authors report high prevalences of autoimmune diseases in CVID, and several mechanisms have been proposed to explain this apparent paradox. Genetic predisposition, under current surveillance, innate and adaptive immunity deficiencies leading to persistent/recurrent infections, variable degrees of immune dysregulation, and possible failure in central and peripheral mechanisms of tolerance induction or maintenance may all contribute to increased autoimmunity.

CONCLUSIONS

Data on the clinical/immunological profile of affected patients and treatment are available mostly concerning autoimmune cytopenias, the most common autoimmune diseases in CVID. Treatment is based on conventional alternatives, in association with short experience with new agents, including rituximab and infliximab. Benefits of early immunoglobulin substitutive treatment and hypothetical premature predictors of autoimmunity are discussed as potential improvements to CVID patients' follow-up.

Anti-inflammatory actions of intravenous immunoglobulin

The remarkable success story of the therapeutic application of pooled immunoglobulin G (IgG) preparations from thousands of donors, the so-called intravenous IgG (IVIG) therapy, to patients with a variety of hematological and immunological disorders began more than half a century ago. Since then, the use of this primary blood product has increased constantly, resulting in the serious danger of shortages in supply. Despite its widespread use and therapeutic success, the mechanisms of action, especially of the anti-inflammatory activity, are only beginning to be understood. In this review, we summarize the clinical use of IVIG for different diseases and discuss recent data on the molecular mechanisms that might explain how this potent drug mediates its activity in vivo.

Grouping of patients with common variable immunodeficiency based on immunoglobulin biosynthesis: comparison with a classification system on CD4-naïve cells

The present study compared two different systems of classification of patients with common variable immunodeficiency (CVID); one based on in vitro immunoglobulin biosynthesis; and another on CD4-naïve cell counts. Peripheral blood mononuclear cells (PBMCs) were isolated from 35 patients with CVID and 20 healthy controls. They were stimulated for the secretion of IgM and IgG after stimulation with Staphylococcus aureus Cowan I (SAC) upon supplementation of interleukin-2 (IL-2) or with pokeweed mitogen. T cell subsets were estimated by flow cytometry. By the first system, patients were classified into group A (n=18) with secretion of neither IgG nor IgM; into group B (n=12) with detectable IgM but no IgG secretion; and into group C (n=5) with IgM and IgG secretion similar to controls. By the second system, patients were classified into group I (n=12) with less than 109 CD4-naïve cells/mul; into group II (n=12) with CD4-naïve cells within 109-225microl(-1); and into group III (n=11) with more than 225 CD4-naïve cells/mul. All groups I-III were defective for in vitro release of IgG and IgM. The likelihood ratio for splenomegaly in patients with <225 CD4-naïve cells/mul was 5.08 (p: 0.024). CD4-naïve cell counts of patients were positively correlated to serum levels of IgG and IgA of patients. The presented results revealed that the former system described adequately the function of B cells and the latter the clinical status of the patient. Our proposal is that both should be used for the characterization of patients with CVID.

Increased serum levels of soluble CD30 in patients with common variable immunodeficiency and its clinical implications

Common variable immunodeficiency (CVID) is a heterogeneous group of disorders, characterized by hypogammaglobulinemia and increased susceptibility to recurrent pyogenic infections, autoimmunity, and malignancies. Twenty-five cases with CVID (18 male and 7 female) and 25 healthy volunteers were investigate in this study. Soluble CD30 (sCD30) serum levels of the subjects were measured and compared. Serum levels of sCD30 in the patients with CVID were significantly increased in comparison with controls (36.93 +/- 32.38 vs 5.27 +/- 1.32 U/ml, P < 0.001). The group of patients with splenomegaly and reversed ratio of CD3+CD4+ T cells/CD3+CD8+ T cells had the highest serum levels of sCD30 (66.01 +/- 43.34 U/ml) in comparison with other patients (P = 0.010). High levels of sCD30 in the CVID patients with splenomegaly and the presence of lymphoma in a patient with the highest level of sCD30 may suggest a soluble form of this marker as a prognostic tool in such diseases.

Expression of Fc gamma and complement receptors in monocytes of X-linked agammaglobulinaemia and common variable immunodeficiency patients

Recently we reported that monocyte phagocytosis and chemotaxis are impaired in X-linked agammaglobulinaemia (XLA) and common variable immunodeficiency (CVI) patients. Few data exist on the in vivo expression of receptors for the constant region of immunoglobulin (IgG) (Fc gammaR) and complement receptors (CR) in these patients. The objective of this study was to investigate the expression of Fc gammaR and CR on monocytes from XLA and CVI patients and compare it to that of healthy controls. Whole blood samples were obtained from 10 patients with XLA, 12 with CVI and 18 healthy controls. Monocyte phenotype was determined by flow cytometry with gating on CD14+ cells. Surface expression of Fc gammaRI (CD64), Fc gammaRII (CD32) and Fc gammaRIII (CD16), CR1 (CD35) and CR3 (CD11b and CD18) was measured by determination of the proportion of CD14+ cells positive for each receptor and by receptor density. Compared to controls, a significantly higher percentage of CD16 and CD35+ monocytes from XLA (P = 0.002 and P = 0.007, respectively) were observed. The relative fluorescence intensity (RFI) expression of Fc gammaRII (CD32) and Fc gammaRIII (CD16) were significantly lower on CVI monocytes compared to controls (P = 0.001 and P = 0.035, respectively). XLA patients, who have a reduction of Bruton's tyrosine kinase (Btk), showed normal or increased percentages of monocytes expressing Fc gamma and complement receptors. CVI patients, who have normal expression of Btk, showed reduced expression of CD16 and CD32 on monocytes. Inefficient chemotaxis and phagocytosis, reported previously in XLA patients, could be due to defects of cytoplasmatic transduction mechanisms.

Genetic defects in common variable immunodeficiency

Common variable immunodeficiency (CVID) is the most frequent clinically manifested primary immunodeficiency. According to clinical and laboratory findings, CVID is a heterogeneous group of diseases. Recently, the defects of molecules regulating activation and terminal differentiation of B lymphocytes have been described in some patients with CVID. In this study, we show the overview of deficiencies of inducible costimulator, transmembrane activator and calcium-modulator and cytophilin ligand interactor, CD19 molecules, their genetic basis, pathogenesis and clinical manifestations.

Intravenous Immunoglobulins in Autoimmune and Inflammatory Diseases: A Mechanistic Perspective

Initially used for the treatment of immunodeficiencies, intravenous immunoglobulins (IVIg) have increasingly been used as immunomodulatory agents in autoimmune and inflammatory disorders. The mode of action of IVIg is enigmatic, probably involving Fc-dependent and/or F(ab')2-dependent nonexclusive mechanisms of action. IVIg broadly interacts with the different components of the immune system: cytokines, complement, Fc receptors, and several cell surface immunocompetent molecules. IVIg has also an impact on effector functions of immune cells. These mechanisms of action of IVIg reflect the importance of natural antibodies in the maintenance of immune homeostasis. We discuss here the recent advances in the understanding of immunoregulatory effects of IVIg, and we pointed out the need for new strategies to overcome the predicted increasing worldwide shortage of IVIg.

Intravenous immunoglobulin in autoimmune and inflammatory diseases: More than mere transfer of antibodies

Initially used for the treatment of immunodeficiencies, intravenous immunoglobulin (IVIg) has increasingly been used as an immunomodulatory agent in immune thrombocytopenic purpura, autoimmune neuropathies, systemic lupus erythematosus, myasthenia gravis, Guillain-Barré syndrome, and Kawasaki disease. Although IVIg benefits have been reported in many autoimmune and systemic inflammatory diseases, its mechanisms of immunomodulation are not fully understood and probably involve Fc-dependent and/or F(ab')(2)-dependent mutually non-exclusive effects. These mechanisms of action of IVIg reflect the importance of natural antibodies in the maintenance of immune homeostasis. We discuss here the recent advances in the understanding of immunoregulatory effects of IVIg.

Common variable immune deficiency and lung transplantation

We report on a male patient with bronchiectasis secondary to common variable immune deficiency (CVID) receiving lung transplantation. The patient had been diagnosed with CVID many y prior to right-sided single lung transplantation and was receiving appropriate immunoglobulin substitution therapy. He received antithymocyte globulin induction and maintenance triple therapy with cyclosporine, azathioprine and prednisolone. The early post-operative course was complicated by the development of severe acute cellular rejection and organizing pneumonia. Despite immunoglobulin replacement and antifungal prophylaxis and treatment, Aspergillus fumigatus was repeatedly cultured from bronchoalveolar lavage fluid, 18 months after transplantation. The patient died following a protracted period of repeated hospital admissions, 46 months after transplantation. A review of the literature suggests that many CVID patients appear to have had a complicated post-operative course after lung- and other solid-organ transplantation, and highlights the need for the establishment of international registries for transplanted patients with uncommon conditions.

Utilisation des immunoglobulines polyclonales intraveineuses dans les pathologies auto-immunes et inflammatoires

Initially used for the treatment of immunodeficiencies, intravenous immunoglobulins (IVIg) have increasingly been used as immunomodulatory agent in autoimmune and inflammatory disorders. The mode of action of IVIg is enigmatic, probably involving Fc-dependent and/or F(ab')2-dependent non-exclusive mechanisms of action. IVIg broadly interacts with the different components of the immune system: cytokines, complement, Fc receptors and several cell surface immunocompetent molecules. IVIg also has an impact on effector functions of immune cells. These mechanisms of action of IVIg reflect the importance of natural antibodies in the maintenance of immune homeostasis. We discuss here the recent advances in the understanding of immunoregulatory effects of IVIg, and we pointed out the need of new strategies to overcome the predicted increasing worldwide shortage of IVIg.

Intravenous immunoglobulin: an update on the clinical use and mechanisms of action

Initially used as a replacement therapy for immunodeficiency diseases, intravenous immunoglobulin (IVIg) is now widely used for a number of autoimmune and inflammatory diseases. Considerable progress has been made in understanding the mechanisms by which IVIg exerts immunomodulatory effects in autoimmune and inflammatory disorders. The mechanisms of action of IVIg are complex, involving modulation of expression and function of Fc receptors, interference with activation of complement and the cytokine network and of idiotype network, regulation of cell growth, and effects on the activation, differentiation, and effector functions of dendritic cells, and T and B cells.

Monogenetic defects in common variable immunodeficiency: what can we learn about terminal B cell differentiation?

PURPOSE OF REVIEW

In human primary immunodeficiencies, more than 100 different genetic defects have been described. For the most prevalent primary immunodeficiency requiring medical attention, however, termed common variable immunodeficiency, no genetic cause had been defined until recently. In this review we will summarize the current progress in the molecular genetics of common variable immunodeficiency and put them in context with other important developments in the field.

RECENT FINDINGS

In recent years the first three monogenetic defects in the inducible costimulator, transmembrane activator and CAML interactor (TACI), and CD19 were discovered in patients with common variable immunodeficiency revealing a multifaceted genetic background for this disease. As a concise phenotype cannot be assigned to each of these genetic defects, there is a need for further development of classification systems for common variable immunodeficiency and the search of epigenetic factors influencing the course of the disease. Subgroups of common variable immunodeficiency patients with low IgM memory B cells may suffer from an increased rate of infections. Human herpes virus type 8 infections were identified as a risk factor for the development of granulomatous disease complications.

SUMMARY

The pathogenesis of common variable immunodeficiency shows a convergence on impaired terminal B cell differentiation. Recently discovered genetic defects support this view. A combined effort of genetic analysis and standardized assessment of immunological and clinical phenotypes will be necessary to further unravel the conundrum of common variable immunodeficiency.