Low numbers of regulatory T cells in common variable immunodeficiency: association with chronic inflammation in vivo

Evaluation of CD4+CD25+FOXP3+ regulatory T cells function in patients with common variable immunodeficiency

Common variable immunodeficiency (CVID) is one of the predominant antibody disorders where abnormalities in regulatory T cells (Tregs) may result in autoimmunity and chronic inflammation. To evaluate Tegs frequency and function, 13 CVID patients and 10 age- and sex-matched healthy volunteer were enrolled. The percentages of Tregs were calculated using flow cytomety method. For assessment of Treg function, Tregs were isolated and their suppressive functions were determined using Tregs suppression assay. The levels of immunoregulatory cytokines IL-10 and TGF-β produced by Tregs were also measured. Our results revealed that Tregs frequency (P<0.001) and their suppressive functions (P<0.001) were impaired in CVID patients. The level of TGF-β did not differ between CVID patients and controls (p=0.09); while the amount of IL-10 was remarkably decreased in CVID patients (P=0.007). Our findings suggest that disturbed Tregs frequency and their functional characteristics might account for aberrant immune responses observed in CVID patients.

T cell phenotypes in patients with common variable immunodeficiency disorders: associations with clinical phenotypes in comparison with other groups with recurrent infections

Common variable immunodeficiency disorders (CVID) are a group of heterogeneous conditions that have in common primary failure of B cell function, although numerous T cell abnormalities have been described, including reduced proliferative response and reduced regulatory T cells. This study compared the T cell phenotype of CVID patients subdivided into clinical phenotypes as well as patients with partial antibody deficiencies [immunoglobulin (Ig)G subclass deficiency and selective IgA deficiency], X-linked agammaglobulinaemia (XLA) and healthy and disease controls. Absolute numbers of T cell subpopulations were measured by four-colour flow cytometry: naive T cells, central and effector memory and terminally differentiated (TEM) T cells, using CD45RA and CCR7 expression. Early, intermediate and late differentiation status of T cells was measured by CD27/CD28 expression. Putative follicular T cells, recent thymic emigrants and regulatory T cells were also assessed. Significant reduction in naive CD4 T cells, with reduced total CD4 and recent thymic emigrant numbers, was observed in CVID patients, most pronounced in those with autoimmune cytopenias or polyclonal lymphoproliferation. These findings suggest a lack of replenishment by new thymically derived cells. CD8 naive T cells were reduced in CVID patients, most significantly in the autoimmune cytopenia subgroup. There was a reduction in early differentiated CD4 and CD8 T cells and increased CD8 TEM in the CVID patients, particularly autoimmune cytopenia and polyclonal lymphoproliferation subgroups, suggesting a more activated T cell phenotype, due perhaps to an antigen-driven process. XLA patients had significantly reduced putative follicular T cells, which may depend on B cells for survival, while no significant alterations were observed in the T cells of those with IgG subclass deficiency or selective IgA deficiency.

Common variable immunodeficiency: crossroads between infections, inflammation and autoimmunity

Common variable immunodeficiency is a collection of diseases characterized by primary hypogammaglobulinemia. The causes of CVID are extremely heterogeneous and may affect virtually every pathway linked to B cell development and function. Clinical manifestations of CVID mainly include recurrent bacterial infections, but autoimmune, gastrointestinal, lymphoproliferative, granulomatous, and malignant disorders have also been frequently reported as associated conditions. We aimed to focus on the state of the art of the relationship between infections, inflammation and autoimmunity in CVID.

Pathogenesis of autoimmunity in common variable immunodeficiency

Common variable immunodeficiency (CVID) presents in up to 25% of patients with autoimmune (AI) manifestations. Given the frequency and early onset in some patients with CVID, AI dysregulation seems to be an integral part of the immunodeficiency. Antibody-mediated AI cytopenias, most often affecting erythrocytes and platelets make up over 50% of these patients. This seems to be distinct from mainly cell-mediated organ-specific autoimmunity. Some patients present like patients with AI lymphoproliferative syndrome. Interestingly, in the majority of patients with AI cytopenias the immunological examination reveals a dysregulated B and T cell homeostasis. These phenotypic changes are associated with altered signaling through the antigen receptor which may well be a potential risk factor for disturbed immune tolerance as has been seen in STIM1 deficiency. In addition, elevated B cell-activating factor serum levels in CVID patients may contribute to survival of autoreactive B cells. Of all genetic defects associated with CVID certain alterations in TACI, CD19, and CD81 deficiency have most often been associated with AI manifestations. In conclusion, autoimmunity in CVID offers opportunities to gain insights into general mechanisms of human autoimmunity.

The association of the IVS1-397T>C estrogen receptor α polymorphism with the regulatory conditions in longstanding type 1 diabetic girls

Type 1 diabetes is considered as pluricausal disease, whose etiology involves genetic predisposition as well as environmental factors that contribute to disease progression and pathogenesis. Women are believed to be more susceptible to develop autoimmune diseases, which may depend in part on the influence of sex hormones on the immune system. It was shown that estrogens may protect against the development of autoimmune disease by inducing the expansion of regulatory T cell pool and upregulating Foxp3 expression. Foxp3 is a transcription factor that controls the development and suppressive function of naturally occurring regulatory T cells CD4(+)Foxp3(+). Longstanding diabetes type 1 has features of low-grade chronic inflammation which may influence regulatory T cell subset by reducing their numbers or/and inhibiting their suppressive potential. As diabetic type 1 patients are differentiated with regard to metabolic factors, level of glycemic control and systemic inflammatory state, we aimed to examine if this can be associated with IVSI-397T>C estrogen receptor α polymorphism. We examined 93 young regularly menstruating girls with diagnosed type 1 diabetes and 49 healthy age-matched control individuals. The PvuII polymorphism of the ER-α gene was analyzed as well as the serum TNF level and the level of CD4(+)Foxp3(+) regulatory T cells in these individuals. Girls with type 1 diabetes had lower level of CD4(+)Foxp3(+) Tregs than their healthy counterparts. Regulatory T cells from these patients showed also lower expression of Foxp3 than Tregs in healthy, control group. In addition, DM1 girls bearing the CC genotypes showed the highest level of CD4(+)Foxp3(+) Tregs and the lowest TNF serum level in comparison to girls carrying CT or TT genotype. The CC DM1 carriers had also higher serum level of estrogens than girls bearing CT or TT genotype. We propose that different variants of IVS1-397 estrogen receptor α polymorphism may become additional genetic factor that influences regulatory conditions during diabetes type 1 in females.

Isolation, expansion and functional assessment of CD4+CD25+FoxP3+ regulatory T cells and Tr1 cells from uremic patients awaiting kidney transplantation

BACKGROUND

The immunosuppressive properties of regulatory T cells have emerged as an attractive tool for the development of immunotherapies in various disease contexts, e.g. to treat transplantation induced immune reactions. This paper focuses on the process of obtaining and functionally characterizing CD4+CD25+FoxP3+ regulatory T cells and Tr1 cells from uremic patients awaiting kidney transplantation.

METHODS

From October 2010 to March 2011 uremic patients awaiting living donor kidney transplantation, and their corresponding kidney donors, were enrolled in the study. A total of seven pairs were included. Isolation of CD4+CD25+FoxP3+ regulatory T cells was performed by magnetic activated cell sorting of peripheral blood mononuclear cells obtained from the uremic patients. Donor specific Tr1 cells were differentiated by repetitive stimulation of immature CD4+ T cells with immature dendritic cells, with the T cells coming from the future kidney recipients and the dendritic cells from the corresponding kidney donors. Cells were then expanded and functionally characterized by the one-way mixed leukocyte reaction and assessment of IL-10 production. Phenotypic analysis was performed by flow cytometry.

RESULTS

The fraction of CD4+CD25+FoxP3+ regulatory T cells after expansion varied from 39.1 to 50.4% and the cells retained their ability to substantially suppress the mixed leukocyte reaction in all but one patient (3.8-19.2% of the baseline stimulated leukocyte activity, p<0.05). Tr1 cells were successfully differentiated from all but one patient and produced high levels of IL-10 when stimulated with immature dendritic cells (1,275-11,038% of the baseline IL-10 secretion, p<0.05).

CONCLUSION

It is practically feasible to obtain and subsequently expand CD4+CD25+FoxP3+ regulatory T cells and Tr1 cells from uremic patients without loss of function as assessed by in vitro analyses. This forms a base for adoptive regulatory T cell therapy in the setting of living donor kidney transplantation.

Autoimmunity in primary immune deficiency: taking lessons from our patients

The elucidation of the genes leading to selected immune defects has accelerated our understanding of the molecular basis of tolerance in autoimmunity disorders. Mutations in genes of the immune system are known to lead to a catalogue of functional deficits, including loss of activation-induced Fas-mediated apoptosis, an inability to remove self-reactive T and/or B cells and insufficient numbers or functions of regulatory T cells. In most cases, microbial antigen stimulation occurs simultaneously, leading to further inflammatory responses. In each case, probing the molecular pathways involved in these primary immune defects has led to a better understanding of autoimmune diseases in general. While subjects with X-linked agammaglobulinaemia are almost devoid of autoimmune diseases, B cells which are present, but dysfunctional in other defects, lead to a significant incidence of autoimmune disease. Autoimmunity is also particularly common in the antibody deficiency states. Although organ-based autoimmunity also occurs, for unclear reasons the main conditions are immune thrombocytopenia purpura and autoimmune haemolytic anaemia. The common variable immune deficiency subjects most afflicted by these cytopenias are those with specific peripheral blood memory B cell phenotypes. B cells of these subjects have a retained autoimmune potential, lack of somatic hypermutation, profound loss of proliferative potential, accelerated apoptosis and loss of normal Toll-like receptor signalling. Treatment with high-dose immunoglobulin and/or steroids can be helpful, while rituximab provides benefits in the treatment of refractory cytopenias with apparently little risk, even with repeated use, due to ongoing immune globulin therapy.

Autoimmunity in common variable immunodeficiency: correlation with lymphocyte phenotype in the French DEFI study

Common variable immunodeficiency (CVID) is the most frequent clinically expressed primary immunodeficiency in adults and is characterized by primary defective immunoglobulin production. Besides recurrent infectious manifestations, up to 20% of CVID patients develop autoimmune complications. In this study, we took advantages of the French DEFI database to investigate possible correlations between peripheral lymphocyte subpopulations and autoimmune clinical expression in CVID adult patients. In order to analyse homogeneous populations of patients with precise clinical phenotypes, we first focused on patients with autoimmune cytopenia because they represent prototypic autoantibody mediated diseases. In a secondary analysis, we have tested our conclusions including all "autoimmune" CVID patients. We describe one of the largest European studies with 311 CVID patients, including 55 patients with autoimmune cytopenia and 61 patients with clinical or serologic autoimmune expression, excluding autoimmune cytopenia. We clarify previous reports and we confirm a very significant correlation between an increased proportion of CD21(low) B cells and CVID associated autoimmune cytopenia, but independently of the presence of other autoimmune disorders or of splenomegaly. Moreover, in CVID associated autoimmune cytopenia, T cells display an activated phenotype with an increase of HLA-DR and CD95 expression and a decrease in the naïve T cell numbers. Patients with other autoimmune manifestations do not harbour this "T and B cells phenotypic picture". In view of recent findings on CD21(low) B cells in CVID and RA, we suggest that both a restricted subset of B cells and a T cell help are required for a breakdown of B cell tolerance against membrane auto antigens in CVID.

B-cell and T-cell phenotypes in CVID patients correlate with the clinical phenotype of the disease

BACKGROUND

Common variable immunodeficiency (CVID) is a heterogeneous disorder characterized by recurrent infections and defective immunoglobulin production.

METHODS

The DEFI French national prospective study investigated peripheral T-cell and B-cell compartments in 313 CVID patients grouped according to their clinical phenotype, using flow cytometry.

RESULTS

In patients developing infection only (IO), the main B-cell or T-cell abnormalities were a defect in switched memory B cells and a decrease in naive CD4(+) T cells associated with an increase in CD4(+)CD95(+) cells. These abnormalities were more pronounced in patients developing lymphoproliferation (LP), autoimmune cytopenia (AC), or chronic enteropathy (CE). Moreover, LP and AC patients presented an increase in CD21(low) B cells and CD4(+)HLA-DR(+) T cells and a decrease in regulatory T cells.

CONCLUSION

In these large series of CVID patients, the major abnormalities of the B-cell and T-cell compartments, although a hallmark of CVID, were only observed in half of the IO patients and were more frequent and severe in patients with additional lymphoproliferative, autoimmune, and digestive complications.

T-cell response to viral antigens in adults and children with common variable immunodeficiency and specific antibody deficiency

Several T cell abnormalities have been described in common variable immunodeficiency (CVID), a B cell disorder of mainly unknown origin. A subset of CVID patients suffers from frequent reactivations of herpes viruses. We studied T cell function in CVID [and in a subset of paediatric patients with specific antibody deficiency (SAD)] by measuring T cell proliferation and cytokine production in response to herpes virus-antigens in paediatric CVID patients (n=9) and paediatric SAD patients (n=5), in adult CVID patients (n=14) and in healthy controls. Paediatric CVID patients, but not SAD patients, displayed moderately increased CD8+ T cell proliferation in response to cytomegalovirus, human herpes virus type 6B (HHV6-B) and herpes simplex virus compared to controls. CD8+ T cell responses in adult CVID patients tended to be increased in response to cytomegalovirus and herpes simplex virus. In response to stimulation with herpes virus antigens, the proinflammatory cytokines interleukin (IL)-1beta, IL-6, tumour necrosis factor (TNF)-alpha and interferon inducible protein (IP)-10 were produced. Overall, no major differences were detected in cytokine production upon stimulation between patients and controls, although higher IL-10 and IL-12 production was detected in paediatric patients. In conclusion, cellular immunity against herpes virus antigens appears undisturbed in CVID patients, although defects in subpopulations of CVID patients cannot be excluded.

Frequency of Treg cells is reduced in CVID patients with autoimmunity and splenomegaly and is associated with expanded CD21lo B lymphocytes

INTRODUCTION

Common variable immunodeficiency is a heterogeneous antibody deficiency syndrome with autoimmune and inflammatory complications in a significant proportion of patients. The study was designed to evaluate the role of T regulatory (Treg) cells in common variable immunodeficiency (CVID) patients with autoimmunity.

METHODS

The number and frequency of Treg cells (CD4(+), CD25(hi), Foxp3(+)) were evaluated in patients and controls, and Foxp3 expression in different subgroups of CVID patients with common clinical manifestations was compared.

RESULTS

CVID patients had significantly fewer Treg cells than controls, and low frequency of Treg cells was associated with expansion of CD21(lo) B cells in patients. Patients with autoimmunity had significantly reduced frequency but normal numbers of regulatory T cells, whilst patients with splenomegaly had significant reduction in frequency and number of regulatory T cells.

CONCLUSION

Foxp3 is useful on its own or as an adjunct to classify CVID patients although the possibility of reduction in Treg cells as a secondary phenomenon cannot be excluded.

Immunophenotypic profile of T cells in common variable immunodeficiency: is there an association with different clinical findings?

BACKGROUND

A system based on the B-cell phenotype has recently been proposed to classify patients suffering from common variable immunodeficiency (CVID). Immunophenotypic T-cell abnormalities have also been correlated with clinical findings, although they have never been used in classification strategies.

OBJECTIVE

To simultaneously assess T and B-cell subset abnormalities in CVID patients and their relationship with clinical findings. To identify potential immunophenotypic T-cell abnormalities that could be further evaluated in multicenter studies.

PATIENTS AND METHODS

Peripheral blood lymphocytes from 21 CVID patients and 21 healthy donors were stained for T and B-cell subsets, analyzed by flow cytometry, and correlated with clinical characteristics.

RESULTS

Patients classified as MB0 (CD19/CD27+ < 11 %) showed higher percentages of CD4/ CD45RA (87 % vs 67 %, p = 0.028) and lower percentages of CD8/CD45RA+CCR7+ (10 % vs 26 %, p = 0.028) and CD4/CD25+ T-cells (36 % vs 62 %, p = 0.034) than MB2 patients. Even though our cohort was small, we observed a higher prevalence of distinct clinical complications of CVID in patients with B and T-cell abnormalities. Nonmalignant lymphoproliferative disorders and IgG hypercatabolism were more frequently observed in MB0 patients. A higher prevalence of splenomegaly was observed among CVID patients with increased levels of CD4/CD45RA, activated CD4/CD38+DR+, CD8/DR+, and CD8/CD38+ T-cells, as well as in those with lower percentages of CD4/CD45RA+CCR7+ and CD4/CD25+ T-cells. Lymphoproliferative disorders were more prevalent among CVID patients with higher CD4/CD45RA percentages.

CONCLUSION

The study of T-cell subsets warrants further evaluation as a potential tool to better identify CVID patients with distinct clinical profiles.

A decreased frequency of regulatory T cells in patients with common variable immunodeficiency

Introduction

Common variable immunodeficiency disorder (CVID) is a heterogeneous syndrome, characterized by deficient antibody production and recurrent bacterial infections in addition abnormalities in T cells. CD4⁺CD25^high regulatory T cells (Treg) are essential modulators of immune responses, including down-modulation of immune response to pathogens, allergens, cancer cells and self-antigens.

Objective

In this study we set out to investigate the frequency of Treg cells in CVID patients and correlate with their immune activation status.

Materials and Methods

Sixteen patients (6 males and 10 females) with CVID who had been treated with regular intravenous immunoglobulin and 14 controls were enrolled. Quantitative analyses of peripheral blood mononuclear cells (PBMC) were performed by multiparametric flow cytometry using the following cell markers: CD38, HLA-DR, CCR5 (immune activation); CD4, CD25, FOXP3, CD127, and OX40 (Treg cells); Ki-67 and IFN-γ (intracellular cytokine).

Results

A significantly lower proportion of CD4⁺CD25^highFOXP3 T cells was observed in CVID patients compared with healthy controls (P<0.05). In addition to a higher proportion of CD8⁺ T cells from CVID patients expressing the activation markers, CD38⁺ and HLA-DR⁺ (P<0.05), we observed no significant correlation between Tregs and immune activation.

Conclusion

Our results demonstrate that a reduction in Treg cells could have impaired immune function in CVID patients.

Therapeutic approaches to secondary immune thrombocytopenic purpura

Secondary thrombocytopenia is similar to primary or idiopathic thrombocytopenia (ITP) in that it is characterized by reduced platelet production or increased platelet destruction resulting in platelet levels<60,000/microL. Thrombocytopenia can occur from secondary causes associated with chronic disorders or with disturbed immune function due to chronic infections, lymphoproliferative and myeloproliferative disorders, pregnancy, or autoimmune disorders. Diagnosis of secondary ITP in some cases is complex, and the thrombocytopenia can often be resolved by treating the underlying disorder to the extent this is possible. In most cases, treatment is focused on reducing platelet destruction, but, in some cases, treatment may also be directed at stimulating platelet production. The most problematic cases of thrombocytopenia may be seen in pregnant women. This review will address various agents and their utility in treating ITP from secondary causes; in addition, thrombocytopenia in pregnancy, ITP in immunodeficiency conditions, and drug-induced thrombocytopenia will be discussed. Unlike primary ITP, treatment often must be tailored to the specific circumstance underlying the secondary ITP, even if the condition itself is incurable.

Decrease in phenotypic regulatory T cells in subsets of patients with common variable immunodeficiency

Common variable immunodeficiencies (CVID) are a heterogeneous group of antibody deficiency disorders complicated by autoimmune, lymphoproliferative and/or granulomatous manifestations, suggesting variations in immunoregulation. We sought to quantify regulatory CD4 T cells (T(reg) cells) in the blood of CVID patients and to correlate the frequency with clinical manifestations and classification subgroups. Blood samples from 99 CVID patients in Freiburg, London and Sydney, who had been phenotyped clinically and stratified according to their memory B cell phenotype (Freiburg and Paris classification schemes), were analysed for the proportion of T(reg) cells, defined either as CD25(+)/forkhead box P3 (FoxP3)(+), CD25(+)/CD127(low)/FoxP3(+) or CD25(+)/CD127(low) CD4(+) T cells, and results compared with 49 healthy controls. Irrespective of the phenotype used to define them, there was a significant decrease in the T(reg) cell proportion in patients with granulomatous disease and immune cytopenias. This allowed the definition of a subgroup of CVID patients with abnormally low T(reg) cells, which had a higher rate of these two manifestations as well as autoimmune disease in general. There was also a significant reduction in the proportion of T(reg) cells in the Freiburg group Ia compared with other CVID patients and controls, but there were no differences between the Paris groups. The reduction in T(reg) cells in subsets of CVID patients may be relevant to their clinical manifestations, and may contribute to our understanding of the pathogenesis of CVID complications.

Common variable immunodeficiency

Common variable immunodeficiency is the most prevalent clinically significant antibody deficiency at all ages. The disorder is defined principally by characteristic infection susceptibility with hypogammaglobulinemia and impaired-specific antibody response. Several recent large registry-based studies have defined distinct phenotypic subtypes. Several studies have also correlated specific immunologic markers with these phenotypes. The biochemical or genetic abnormality in the majority of patients remains unknown. Recently, several molecular genetic lesions have been defined. Among these, mutations of inducible costimulator, and CD19, appear to be disease causing by themselves. These account for about 1% of cases. Other mutations or polymorphisms, such as in the human homolog of Escherichia coli MutS 5 (MSH5), and transmembrane activator and calcium mobilizing ligand interactor, seem to be disease associated in 5-10% of patients, but may require additional immunologic abnormalities for full expression of the phenotype, as unaffected heterozygotes have also been described.

Reduced frequency of CD4(+)CD25(HIGH)FOXP3(+) cells and diminished FOXP3 expression in patients with Common Variable Immunodeficiency: a link to autoimmunity?

Common Variable Immunodeficiency (CVID) is a primary immunodeficiency disease characterized by defective immunoglobulin production and often associated with autoimmunity. We used flow cytometry to analyze CD4(+)CD25(HIGH)FOXP3(+) T regulatory (Treg) cells and ask whether perturbations in their frequency in peripheral blood could underlie the high incidence of autoimmune disorders in CVID patients. In this study, we report for the first time that CVID patients with autoimmune disease have a significantly reduced frequency of CD4(+)CD25(HIGH)FOXP3(+) cells in their peripheral blood accompanied by a decreased intensity of FOXP3 expression. Notably, although CVID patients in whom autoimmunity was not diagnosed had a reduced frequency of CD4(+)CD25(HIGH)FOXP3(+) cells, FOXP3 expression levels did not differ from those in healthy controls. In conclusion, these data suggest compromised homeostasis of CD4(+)CD25(HIGH)FOXP3(+) cells in a subset of CVID patients with autoimmunity, and may implicate Treg cells in pathological mechanisms of CVID.

Update in understanding common variable immunodeficiency disorders (CVIDs) and the management of patients with these conditions

The common variable immunodeficiency disorders are a mixed group of heterogeneous conditions linked by lack of immunoglobulin production and primary antibody failure. This variability results in difficulty in making coherent sense of either immunopathogenesis or the role of various genetic abnormalities reported in the literature. The recent attempt to collate the varied complications in these conditions and to define particular clinical phenotypes has improved our understanding of these diseases. Once refined and confirmed by other studies, these definitions will facilitate improved accuracy of prognosis and better management of clinical complication. They may also provide a method of analysing outcomes as related to new immunopathological and genetic findings.

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.

Primary immunodeficiencies (PIDs) presenting with cytopenias

Autoimmune manifestations are increasingly being recognized as a component of several forms of primary immunodeficiencies (PID). Defects in purging of self-reactive T and B cells, impaired Fas-mediated apoptosis, abnormalities in development and/or function of regulatory T cells, and persistence of immune activation as a result of inability to clear infections have been shown to account for this association. Among autoimmune manifestations in patients with PID, cytopenias are particularly common. Up to 80% of patients with autoimmune lymphoproliferative syndrome (ALPS) have autoantibodies, and autoimmune hemolytic anemia and immune thrombocytopenia have been reported in 23% and 51% of ALPS patients, and may even mark the onset of the disease. ALPS-associated cytopenias are often refractory to conventional treatment and represent a therapeutic challenge. Autoimmune manifestations occur in 22% to 48% of patients with common variable immunodeficiencies (CVIDs), and are more frequent among CVID patients with splenomegaly and granulomatous disease. Finally, autoimmune cytopenias have been reported also in patients with combined immunodeficiency. In particular, autoimmune hemolytic anemia is very common among infants with nucleoside phosphorylase deficiency. While immune suppression may be beneficial in these cases, full resolution of the autoimmune manifestations ultimately depends on immune reconstitution, which is typically provided by hematopoietic cell transplantation.

Flowcytometric phenotyping of common variable immunodeficiency

BACKGROUND

Common variable immunodeficiency (CVID) comprises heterogeneous antibody deficiency disorders. To classify this heterogeneous syndrome, clinical as well as immunologic parameters have been combined. Flowcytometric analysis of circulating T and B lymphocyte subpopulations has become an important tool in this endeavor of disease classification.

METHODS

Multicolor flowcytometric analysis of circulating lymphocytes.

RESULTS

The flowcytometric analysis of B and T cell subpopulations in the blood of CVID patients has contributed significantly to the identification of separate groups within the CVID population. In addition, the flowcytometric analysis of the inducible costimulator on activated T cells, CD19 and BAFF-R on B cells are valid screening methods for three of the four known genetic defects associated with CVID. Only TACI deficiency can not be sufficiently detected by flowcytometric measures.

CONCLUSIONS

Flowcytometric classification of patients with CVID has become a standard procedure during the diagnostic work up. This should be performed according to common guidelines to guarantee world wide comparability between different immunodeficiency centers.

Chemokines and common variable immunodeficiency; possible contribution of the fractalkine system (CX3CL1/CX3CR1) to chronic inflammation

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by defective immunoglobulin production and high frequency of bacterial infections, autoimmunity and manifestations of chronic inflammation. The chemokine Fractalkine (CX3CL1) and its receptor CX3CR1 is suggested to play an important role in the pathogenesis of several inflammatory disorders. We hypothesized that enhanced CX3CL1/CX3CR1 interaction could be involved in the chronic inflammation characterising subgroups of CVID. CVID patients were characterized by raised plasma levels of CX3CLl and enhanced expression of its corresponding receptor CX3CR1 on CD4(+) and CD8(+) T cells, including both CD45RA(+) and CD45RA(-) subsets. CX3CR1 expression was particularly enhanced in patients characterized by chronic inflammation in vivo. The high expression of the receptor in CVID patients was accompanied by enhanced chemotactic, adhesive, and other inflammatory cell responses to stimulation with CX3CL1. Our findings suggest that increased CX3CL1/CX3CR1 interaction could contribute to the inflammatory phenotype seen in subgroups of CVID patients.

Immune dysregulation in primary immunodeficiency disorders

The past several years have brought an increased awareness of the prevalence of autoimmunity and immune dysregulation among patients who have primary immunodeficiency disorders (PIDD). The recent clinical and molecular definition of PIDD, in which the primary defect is in the immunoregulatory compartment of the immune system, has offered insight into the basic mechanisms of immune tolerance, which has provided new targets and new techniques to study immune tolerance in PIDD. Many of these studies have focused on the presence and function of regulatory T (T(REG)) cells in PIDD, particularly since the discovery of murine and human syndromes associated with T(REG) deficiency. This article focuses on the current state of knowledge regarding the role of T(REG) in various PIDD that have clinical features indicative of dysregulated immunity.

Lymphoma in common variable immunodeficiency: interplay between immune dysregulation, infection and genetics

PURPOSE OF REVIEW

Common variable immunodeficiency represents the largest group of primary immunodeficiency patients. The variable clinical manifestations include an increased susceptibility to chronic infections, granulomatous disease and the lymphoproliferative predisposition to develop lymphoma. This review discusses the latest insights into common variable immunodeficiency and uses common variable immunodeficiency as a model to examine the links between immunodeficiency and chronic infections in causing lymphoma.

RECENT FINDINGS

Newly identified disease genes within the common variable immunodeficiency population, have advanced the understanding of human immunodeficiency and the molecular basis of B-cell biology. Refined laboratory techniques have better defined this heterogeneous condition by classifying the underlying B-cell and T-cell abnormalities. New sensitive methods have also identified the presence of persistent infections that may play a role in the development of lymphoma.

SUMMARY

There are several reasons for an increased risk of lymphoma in common variable immunodeficiency patients. These include genetics, immune dysregulation, radiosensitivity and chronic infections such as Helicobacter pylori, human herpes virus type 8 and cytomegalovirus. Chronic infections may enhance the development of lymphoma in an antigen specific manner. The interaction between chronic infections and the development of lymphoma is still unclear but studies to clarify this may lead to prevention measures and lymphoma reduction strategies.

Primary immunodeficiencies unravel critical aspects of the pathophysiology of autoimmunity and of the genetics of autoimmune disease

BACKGROUND

Primary Immunodeficiencies (PIDs) represent unique opportunities to understand the operation of the human immune system. Accordingly, PIDs associated with autoimmune manifestations provide insights into the pathophysiology of autoimmunity as well as into the genetics of autoimmune diseases (AID). Epidemiological data show that there are PIDs systematically associated with AID, such as immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome (IPEX), Omenn syndrome, autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), autoimmune lymphoproliferative syndrome (ALPS), and C1q deficiency, while strong associations are seen with a handful of other deficits.

CONCLUSION

We interpret such stringent disease associations, together with a wealth of observations in experimental systems, as indicating first of all that natural tolerance to body components is an active, dominant process involving many of the components that ensure responsiveness, rather than, as previously believed, the result of the mere purge of autoreactivities. More precisely, it seems that deficits of Treg cell development, functions, numbers, and T cell receptor repertoire are among the main factors for autoimmunity pathogenesis in many (if not all) PIDs most frequently presenting with autoimmune features. Clearly, other pathophysiological mechanisms are also involved in autoimmunity, but these seem less critical in the process of self-tolerance. Comparing the clinical picture of IPEX cases with those, much less severe, of ALPS or APECED, provides some assessment of the relative importance of each set of mechanisms.

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.

Common variable immunodeficiency disorders: division into distinct clinical phenotypes

The European Common Variable Immunodeficiency Disorders registry was started in 1996 to define distinct clinical phenotypes and determine overlap within individual patients. A total of 7 centers contributed patient data, resulting in the largest cohort yet reported. Patients (334), validated for the diagnosis, were followed for an average of 25.6 years (9461 patient-years). Data were used to define 5 distinct clinical phenotypes: no complications, autoimmunity, polyclonal lymphocytic infiltration, enteropathy, and lymphoid malignancy. A total of 83% of patients had only one of these phenotypes. Analysis of mortality showed a considerable reduction in the last 15 years and that different phenotypes were associated with different survival times. Types of complications and clinical phenotypes varied significantly between countries, indicating the need for large, international registries. Ages at onset of symptoms and diagnosis were shown to have a Gaussian distribution, but were not useful predictors of phenotype. The only clinical predictor was polyclonal lymphocytic infiltration, which was associated with a 5-fold increased risk of lymphoid malignancy. There was widespread variation in the levels of serum immunoglobulin isotypes as well as in the percentages and absolute numbers of B cells, confirming the heterogeneity of these conditions. Higher serum IgM and lower circulating CD8 proportions were found to be predictive markers for polyclonal lymphocytic infiltration and autoimmunity, respectively.