Comparison of various classifications for patients with common variable immunodeficiency (CVID) using measurement of B-cell subsets

BACKGROUND

Common variable immunodeficiency (CVID) is a heterogeneous disease, characterised by hypogammaglobulinaemia leading to recurrent infections and various complications. The aim of this study was to classify CVID patients based on four known classifications (Paris, Freiburg, EUROclass, and B-cell patterns) by measurement of B-cell subsets and to assess the relation of each classification with clinical manifestations.

METHODS

We measured all B-cell subsets as both absolute count and percentage in 30 CVID patients and 30 healthy individuals using four-colour flow cytometry. Moreover, we evaluated antibody responses to pneumococcal vaccine in patients.

RESULTS

A significant reduction in percentage of terminal B-cell subsets (total, marginal zone-like, switched memory, IgM-only memory, total memory B-cells and plasmablast) and absolute count of all B-cell subsets along with a strong increase in CD21^low B-cells has been observed in patients. Patients with splenomegaly and hepatomegaly clustered in group Ia, smB+21^low and group 1 based on known classifications, and significantly tended to have a decreased transitional and marginal zone-like B-cells count, as well as an increase in CD21^low B-cell counts. Patients with lymphadenopathy, bronchiectasis and allergy had a significant decrease in absolute count of total memory, switched memory and total B-cells, respectively.

CONCLUSION

Classification of patients could provide useful information to guide clinicians in long-term follow-up of CVID patients. Our data demonstrate that it may be more accurate to use absolute counts of B-cell subpopulations in CVID patients because absolute counts of B-cell subsets are more associated with clinical manifestations compared with their percentage and also four known classifications.

Telomere-dependent replicative senescence of B and T cells from patients with type 1a common variable immunodeficiency

A subset of patients with common variable immunodeficiency (CVID), group 1a of the Freiburg classification, is characterized by increased B cells expressing low levels of CD21 (CD21(low) ), lymphoproliferation and autoimmunity. The CD21(low) B cells have been shown to be profoundly anergic, and defects of BCR-mediated calcium signaling and of T cells have been described in CVID 1a. We found that also the classical naïve B cells from CVID 1a patients, but not from CVID non-1a patients, proliferated poorly. The B cells of CVID 1a patients had a reduced capacity to divide reminiscent of the proliferative arrest associated with replicative senescence. Thus, we investigated whether lymphocyte dysfunction in CVID 1a was related to telomere-dependent replicative senescence, and found that both the B and the T cells from CVID 1a patients had significantly shorter telomeres compared with B and T cells from CVID non-1a patients. Telomere lengths in B and T cells were significantly correlated, indicating that the rate of telomere attrition in lymphocytes is an individual characteristic of CVID patients. Our findings suggest that telomere-dependent replicative senescence contributes to the immune dysfunction of CVID 1a patients, and may provide an important clue for a better understanding of the pathogenesis of CVID.

Serum bactericidal antibody responses to meningococcal polysaccharide vaccination as a basis for clinical classification of common variable immunodeficiency

Common variable immunodeficiency (CVID) is a heterogeneous group of disorders characterized by hypogammaglobulinemia and increased susceptibility to recurrent pyogenic infections. This study was performed to subclassify CVID on the basis of the bactericidal antibody responses of patients to polysaccharide meningococcal vaccine. Twenty-five patients with CVID (18 male and 7 female) and 25 healthy volunteers received meningococcal polysaccharide vaccine A + C. Serum bactericidal antibody (SBA) titers were measured at baseline and after 3 weeks. Response was correlated with clinical and immunological manifestations of CVID. Twenty-four (96%) of the 25 normal controls had a protective SBA titer of > or = 8 postvaccination, whereas only 16 (64%) of the 25 CVID patients had a protective titer (P value = 0.013). Among the patients with CVID who were nonresponders, there were significantly increased rates of bronchiectasis (P = 0.008), splenomegaly (P = 0.016), and autoimmunity (P = 0.034) in comparison with patients who had protective SBA titers. A reversed CD4/CD8 ratio was more common in the nonresponder group of patients (P = 0.053). We conclude that individuals with CVID who cannot produce protective postvaccination titers after receiving meningococcal polysaccharide vaccine are more likely to exhibit bronchiectasis, splenomegaly, and autoimmune diseases. Vaccination response may define subgroups of patients with CVID, enabling more effective monitoring and therapeutic strategies.

The EUROclass trial: defining subgroups in common variable immunodeficiency

The heterogeneity of common variable immunodeficiency (CVID) calls for a classification addressing pathogenic mechanisms as well as clinical relevance. This European multicenter trial was initiated to develop a consensus of 2 existing classification schemes based on flowcytometric B-cell phenotyping and the clinical course. The clinical evaluation of 303 patients with the established diagnosis of CVID demonstrated a significant coincidence of granulomatous disease, autoimmune cytopenia, and splenomegaly. Phenotyping of B-cell subpopulations confirmed a severe reduction of switched memory B cells in most of the patients that was associated with a higher risk for splenomegaly and granulomatous disease. An expansion of CD21(low) B cells marked patients with splenomegaly. Lymphadenopathy was significantly linked with transitional B-cell expansion. Based on these findings and pathogenic consideration of B-cell differentiation, we suggest an improved classification for CVID (EUROclass), separating patients with nearly absent B cells (less than 1%), severely reduced switched memory B cells (less than 2%), and expansion of transitional (more than 9%) or CD21(low) B cells (more than 10%). Whereas the first group contains all patients with severe defects of early B-cell differentiation, severely reduced switched memory B cells indicate a defective germinal center development as found in inducible constimulator (ICOS) or CD40L deficiency. The underlying defects of expanded transitional or CD21(low) B cells remain to be elucidated. This trial is re-gistered at http://www.uniklinik-freiburg.de/zks/live/uklregister/Oeffentlich.html as UKF000308.

Active vaccination in patients with common variable immunodeficiency (CVID)

Active vaccination of CVID patients with standard vaccines has rarely been studied in depth although some patients have been shown to develop transient vaccine-specific immunity. We addressed the question whether these patients can be identified by functional classification of their B cell subsets in vitro. Twenty-one CVID patients receiving regular IgG substitution were immunized with anti-peptide and anti-polysaccharide vaccines. Humoral vaccination responses were compared to the numbers of circulating memory B cells, CD21(low) B cells and the capacity to produce antibodies in vitro. Our findings allow four conclusions: (1) positive vaccination responses are not contradictory to the diagnosis of CVID; they occurred against polypeptide vaccines in 23% and against polysaccharide antigens in 18% of all vaccinations. (2) Class-switched antibody responses occur preferentially in patients of CVID group II. (3) A normal percentage of IgM memory B cells is necessary but not sufficient for a vaccination response to polysaccharide antigens. (4) Active vaccination in addition to IgG replacement therapy should be performed in patients of CVID type II - especially in case of vaccines for which passive protection cannot be guaranteed.

Unravelling the complexity of T cell abnormalities in common variable immunodeficiency

We investigated several phenotypic and functional parameters of T cell-mediated immunity in a large series of common variable immunodeficiency (CVID) patients. We demonstrated that the vast majority of CVID patients presented multiple T cell abnormalities intimately related among them, the severity of which was reflected in a parallel loss of CD4+ naive T cells. A strong correlation between the number of CD4+ naive T cells and clinical features was observed, supporting the subgrouping of patients according to their number of naive CD4+ T lymphocytes. A reduced thymic output and disrupted CD4+ and CD8+ TCR repertoires paralleled the contraction of CD4+ naive T cell pools. The evaluation of activation markers and cytokine production indicated a strong T cell activation that was significantly related to the increased levels of T cell turnover and apoptosis. Finally, discrete genetic profiles could be demonstrated in groups of patients showing extremely diverse T cell subset composition and function. Naive CD4+ T cell levels were significantly associated with the switched memory B cell-based classification, although the concordance between the respective subgroups did not exceed 58.8%. In conclusion, our data highlight the key role played by the T cell compartment in the pathogenesis of CVID, pointing to the need to consider this aspect for classification of this disease.

Deconstructing common variable immunodeficiency by genetic analysis

Common variable immunodeficiency (CVID) is the most common symptomatic primary immunodeficiency. Patients have recurrent bacterial infections and an increased risk of developing autoimmune diseases, lung damage, and selected cancers. Since 2003, four genes have been shown to be mutated in CVID patients: ICOS, TNFRSF13B (encoding TACI), TNFRSF13C (encoding BAFF-R) and CD19. Heterozygous mutations in TNFRSF13B are also associated with CVID, whereas the other three genes are purely recessive. Recent genetic linkage studies have also identified possible loci for dominant CVID genes on chromosomes 4q, 5p and 16q. These findings markedly improved the genetic diagnosis of CVID and point towards new strategies for future genetic studies. In addition, some CVID genes might be relevant to more common diseases such as asthma and stroke.

Analysis of class-switched memory B cells in patients with common variable immunodeficiency and its clinical implications

BACKGROUND

Common variable immunodeficiency (CVID) comprises a heterogeneous group of primary immunodeficiency disorders characterized by hypogammaglobulinemia leading to recurrent infections. Some patients with CVID are more susceptible to earlier onset of respiratory disease and bronchiectasis. It has been suggested that memory B cells, characterized by CD27 expression, can be used as a means to classify subsets of CVID patients.

OBJECTIVE

The aim of this study was to classify a sample of Iranian patients with CVID by quantification of peripheral blood memory B cells and immature B cells and to assess the relationship between this classification and the clinical characteristics of the patients.

METHODS

The study included 29 patients with CVID and 20 healthy controls. Patients were grouped as follows, according to the quantification of peripheral memory B cells: group I had less than 0.4% switched memory B cells (CD27+, immunoglobulin [Ig] M-, IgD-) in peripheral blood lymphocytes (PBL), while in group II switched memory B cells represented more than 0.4% of PBL. Group I patients were further subdivided into groups Ia and Ib according to the proportion of CD21- peripheral B cells. The clinical and laboratory findings for the patients were then compared among the 3 groups.

RESULTS

The percentage of switched memory B cells (CD27+IgM-IgD- cells in peripheral B lymphocytes) was markedly reduced in CVID patients compared with controls (P < .001). This percentage was less than 0.4% (group I) in 20 patients (69%) (P < .05). In the remaining 9 patients (group II) and all healthy controls, the percentage was greater than 0.4%. Bronchiectasis was more frequent in group I than group II (P < .05). Following subdivision of group I patients into groups Ia and Ib based on CD21 peripheral B cells, the rate of autoimmunity was found to be much higher in group Ia than group Ib.

CONCLUSIONS

CVID patients with reduced numbers of switched memory B cells are more prone to recurrent respiratory infections and development of bronchiectasis, and as such, need more special care than other CVID patients. Thus, classification of CVID patients by assessment of switched memory B cells could help physicians to predict clinical prognosis of these patients.

Age dependency and mutual relations in T and B lymphocyte abnormalities in common variable immunodeficiency patients

Common variable immunodeficiency (CVID) is primary hypogammaglobulinaemia with an unknown aetiopathogenesis. Although various abnormalities of T and B cells have been described, their pathogenetic roles are unclear. We determined T and B lymphocyte subsets known to be abnormal in CVID in order to disclose possible relations between numerical abnormalities in those cells. Markers associated with B cell development (CD21, CD27, IgM, IgD) were determined on B lymphocytes (CD19+); T lymphocyte development (CD45RA, CD45RO, CD62L) and activation markers (CD25, CD27, CD28, CD29, CD38, CD57, HLA-DR) were determined on CD4+ and CD8+ T lymphocytes in 42 CVID patients and in 33 healthy controls. Abnormalities in CD4+ T lymphocyte activation markers (increase in CD29, HLA-DR, CD45RO, decrease in CD27, CD62L, CD45RA) were observed particularly in patients with a decreased number of memory (CD27+) and mature (CD21+) B cells (group Ia according to the Freiburg group's classification), while abnormalities observed in CD8+ cells (increase in CD27 and CD28 and decrease in HLA-DR, CD57 and CD38) did not depend upon grouping patients together according to B lymphocyte developmental subpopulations. We observed correlations between immature B cells (IgM+ CD21-) and expression of CD27, CD62L, CD45RA, CD45RO and HLA-DR on CD4+ T cells in CVID patients but not in the control group. The expression of CD27 and CD45RA on CD4+ T lymphocytes, such as the percentage of IgD+ CD27- and IgD+ CD27+ cells in B lymphocytes, showed age dependency to be more significant than in the control group. Our study demonstrates that T and B lymphocyte abnormalities in CVID are partially related to each other. Some of those abnormalities are not definite, but may evolve with age of the patient.

Tackling the heterogeneity of CVID

PURPOSE OF REVIEW

Common variable immunodeficiency is clinically the most relevant primary immunodeficiency of the adult. Its heterogeneity has hindered progress in the pathogenetic understanding of the majority of common variable immunodeficiency patients. This abstract summarizes recent aspects of the field and emphasizes the need for a commonly accepted approach to classify common variable immunodeficiency.

RECENT FINDINGS

In the last 2 years, the first genetic defects underlying common variable immunodeficiency, including ICOS, TACI, BAFF-R and CD19, have been identified. The analysis of dendritic cells demonstrated alterations in a majority of patients in addition to the disturbed T and B-cell function. Several changes of the adaptive immune system might be secondary to an underlying chronic inflammatory setting possibly due to a HHV8 infection in a subgroup of patients with granulomatous disease, autoimmune phenomena and T-cell dysfunction. The occurrence of granulomatous inflammation is associated with a worse prognosis compared with common variable immunodeficiency patients without granuloma.

SUMMARY

The pathogenesis of common variable immunodeficiency includes disturbances of the adaptive as well as innate immune system. Identified monogenic defects account for about 10% of cases, leaving the majority of defects undefined and certainly in part epigenetic. To combine the known aspects of the pathogenesis of common variable immunodeficiency to a conclusive picture, the clinical and immunologic phenotyping of patients needs to be standardized.

CD8+HLA-DR+ T lymphocytes are increased in common variable immunodeficiency patients with impaired memory B-cell differentiation

The recently proposed Piqueras classification of common variable immunodeficiency (CVID) patients is based on flow cytometric quantification of IgD class-switched and CD27 membrane-expressing mature blood B cells. But, many patients also have circulating T cells with immunophenotypic abnormalities, often associated with clinical complications, such as splenomegaly, autoimmune disease, lymphoid proliferation and/or granulomatosis. In 50 unselected CIVD patients, classified according to CD27 and IgD B-cell expression, we analyzed T-lymphocyte subsets according to their expression of HLA-DR and intracellular perforin and/or granzyme B in CD8+ T lymphocytes, CCR7 and CD45RA. CD3+DR+ T-lymphocyte percentages, predominantly CD8+DR+, were significantly higher in patients with clinical complications. MB0 classified patients, characterized by fewer CD27+ B cells, had higher percentages of CD8+DR+ T lymphocytes expressing perforin and/or granzyme with a differentiated effector (CCR7- and CD45RA+) phenotype. In contrast, MB2 patients (with normal CD27+ and IgD- B cells) were free of clinical complications and showed no signs of T-cell activation. MB1 patients (normal CD27+ numbers but fewer IgD- B cells) were either clinically normal or had complications. Combining the set of markers described herein might better define homogeneous groups of patients for etiological studies and clearly segregate patients with clinical complications.

Measurement of peripheral B cell subpopulations in common variable immunodeficiency (CVID) using a whole blood method

Recent reports have described reduced populations of CD27+ memory B cells and increased percentages of undifferentiated B cells in peripheral blood of patients with common variable immunodeficiency (CVID). This work has prompted two attempts to classify CVID based on rapid flow cytometric quantification of peripheral blood memory B cells and immature B cells. Evidence to support the hypothesis that such in vitro B cell classification systems correlate with clinical subtypes of CVID is being sought. For the classification to be useful in routine diagnosis, it is important that the flow cytometric method can be used without prior separation of peripheral blood mononuclear cells (PBMC). We have examined 23 CVID patients and 24 controls, using both PBMC and whole blood, and find an excellent correlation between these methods. The reproducibility of the method was excellent. We classified the CVID patients by all three of the existing classifications, including secretion of immunoglobulin by B cells in vitro as described by Bryant, as well as the more recent flow cytometric classification methods. Only one patient changed classification as a result of using whole blood.

Common variable immunodeficiency patient classification based on impaired B cell memory differentiation correlates with clinical aspects

Common variable immunodeficiency (CVID) is a very heterogeneous syndrome defined by impaired immunoglobulin production. The functional classification of CVID patients on the basis of in vitro immunoglobulin production is time consuming and has never shown any predictive value. We propose a classification based on the quantitative repartition of naive/memory B cells according to the dual expression of IgD and CD27. Fifty-seven patients were categorized into three groups: Group MB2 (11 patients, 19%) with normal memory B cells; Group MB1 (19 patients, 33%) with defective switched memory (IgD-CD27+) but normal nonswitched memory B cells (IgD+CD27+); Group MB0 (27 patients, 47%) with almost no memory B cells. In addition, a downexpression of activation markers (CD25, CD21, CD80, CD86) on B cells characterized the group MB1 patients and was associated with an upexpression of activation markers (HLA-DR, CD95, CD57) on T cells. This classification correlates with some clinical aspects showing a higher prevalence of splenomegaly (16/27, 59%), lymphoid proliferation (13/27, 48%) and granulomatous disease (12/27, 44%) in group MB0. Splenomegaly was also frequent in group MB1 (8/19, 42%). In contrast, autoimmunity was observed with similar prevalence in all three groups. Moreover, by analyzing B cell phenotype, immunoglobulin transcript expression, and somatic mutations, we propose different putative mechanisms responsible for impaired B cell activation and memory differentiation in this syndrome.

[Classification and diagnosis of immunodeficiency syndromes]

Primary immunodeficiency diseases of the adult are rare disorders, but often lead to serious consequences. Therefore an early diagnosis is critical. The variety in the clinical presentation, the complexity of the immune system and the ongoing discovery of new defects render it a difficult area for the involved physician. Due to the often imprecise complaint of a weak immune system the primary task is the identification of patients with true immunodeficiency. Subsequently, the immune defect needs to be identified in collaboration with a center for immunodeficiency disorders. The diagnostic procedure is dependent on the pattern of infections and follows a defined series of steps. This procedure should prevent costly diagnostic evaluation when not indicated, and also prevent the delayed diagnosis of patients with manifest immunodeficiency disease.

Semiquantitative evaluation of mRNAs for the membranous form of immunoglobulin heavy chain is useful for investigating the etiology in CVID

Common variable immunodeficiency (CVID) is a primary antibody deficiency syndrome characterized by defective B-cell maturation and antibody formation resulting in low serum antibody levels of all immunoglobulin (Ig) isotypes. To investigate the pathogenesis of CVID, we developed a set of competitive polymerase chain reaction for membrane-bound Ig heavy chain (mHC) mRNAs for IgM, IgG and IgA. Data on three children with CVID in group A of Bryant's classification were analysed. All the three mHC mRNA levels in Patient 1 were almost same as those in healthy controls. In Patient 2, mHC mRNA for IgM was detected at a level similar to that in controls, but mHC mRNAs for IgG and IgA heavy chains were not detected. In Patient 3, all the three mHC mRNAs were undetectable. Our data suggest that a different molecular basis exists in these patients with CVID even though all belong to group A of Bryant's classification. Use of our method facilitates a better understanding of molecular events in CVID patients and may be useful for precise classifications of CVID.

Expansion of CD19(hi)CD21(lo/neg) B cells in common variable immunodeficiency (CVID) patients with autoimmune cytopenia

Common variable immunodeficiency (CVID) is characterized by a severe hypogammaglobulinemia. While the clinical picture is dominated by recurrent respiratory and gastrointestinal infections, a subgroup of up to 30% of the patients develops additional autoimmune phenomena, including thrombocytopenia and autoimmune hemolytic anemia. So far no classification allowed a prediction of the coincidence of immunodeficiency and autoimmunity. Here, we propose the size of the peripheral CD19(hi)CD2(lo/neg) B cell pool as a marker for CVID patients with autoimmune cytopenia and splenomegaly. Interestingly similar B cell populations are also found in patients with SLE and may not only be an epiphenomenon of the disease.

Severe deficiency of switched memory B cells (CD27(+)IgM(-)IgD(-)) in subgroups of patients with common variable immunodeficiency: a new approach to classify a heterogeneous disease

Hypogammaglobulinemia is the hallmark of common variable immunodeficiency (CVID) syndrome, a heterogeneous disorder predisposing patients to recurrent bacterial infections. In this study, we investigated the peripheral B-cell compartment of 30 well-characterized CVID patients in comparison to 22 healthy controls. Flow cytometric analysis of peripheral blood lymphocytes revealed a reduction of class-switched CD27(+)IgM(-)IgD(-) memory B cells below 0.4% in 77% of our patients (group I), while this B-cell subpopulation exceeded 0.5% in all healthy donors and in 23% of CVID patients (group II). These results correlate well with the capacity of peripheral blood lymphocytes to produce immunoglobulins in vitro upon stimulation with Staphylococcus aureus Cowan I (SAC) plus interleukin-2 because the production of immunoglobulin G in vitro is entirely dependent on the presence of switched memory B cells. The subdivision of group I into patients with an increased proportion of CD21(-) peripheral B cells (> 20%; group Ia) and patients with normal percentages of CD21(-) B cells (< 20%; group Ib) revealed a significant clustering of patients with splenomegaly and autoimmune cytopenias in group Ia. Based on these observations, we propose a fast and reliable new classification for CVID patients by flow cytometric quantification of class-switched memory and immature B cells in the peripheral blood of patients. Our results point toward defects at various stages of B-cell differentiation in CVID subgroups and support the value of a B-cell-oriented classification principle. A consensus on this new classification system will hopefully provide a tool for rapidly defining homogeneous subgroups of CVID for functional studies and genetic linkage analysis.

Alterations of the X-linked lymphoproliferative disease gene SH2D1A in common variable immunodeficiency syndrome

X-linked lymphoproliferative (XLP) disease is a primary immunodeficiency caused by a defect in the SH2D1A gene. At least 3 major manifestations characterize its clinical presentation: fatal infectious mononucleosis (FIM), lymphomas, and immunoglobulin deficiencies. Common variable immunodeficiency (CVID) is a syndrome characterized by immunoglobulin deficiency leading to susceptibility to infection. In some patients with CVID, a defective btk or CD40-L gene has been found, but most often there is no clearly identified etiology. Here, 2 unrelated families in whom male members were affected by CVID were examined for a defect in the XLP gene. In one family previously reported in the literature as having progressive immunoglobulin deficiencies, 3 brothers were examined for recurrent respiratory infections, whereas female family members showed only elevated serum immunoglobulin A levels. A grandson of one of the brothers died of a severe Aspergillus infection secondary to progressive immunoglobulin deficiency, FIM, aplastic anemia, and B-cell lymphoma. In the second family, 2 brothers had B lymphocytopenia and immunoglobulin deficiencies. X-linked agammaglobulinemia syndrome was excluded genetically, and they were classified as having CVID. The occurrence of FIM in a male cousin of the brothers led to the XLP diagnosis. Because the SH2D1A gene was found altered in both families, these findings indicate that XLP must be considered when more than one male patient with CVID is encountered in the same family, and SH2D1A must be analyzed in all male patients with CVID. Moreover, these data link defects in the SH2D1A gene to abnormal B-lymphocyte development and to dysgammaglobulinemia in female members of families with XLP disease.

Impaired up-regulation of CD86 in B cells of "type A" common variable immunodeficiency patients

Common variable immunodeficiency (CVID) is characterized by defective B cell maturation and antibody formation resulting in low serum antibody levels of most or all Ig isotypes. A specific subgroup of patients ("type A") has normal numbers of mature surface (s)IgM / sIgD- positive circulating B cells. However, since these lymphocytes do not respond to in vitro stimulation by differentiation and Ig synthesis, they seem to suffer from so far unknown intrinsic defects. Analyzing the expression pattern of a large set of B cell activation-specific surface markers, we found that type A CVID patients show a highly reduced expression of the CD28 / CTLA-4 ligand CD86 (B7-2) and of the lymphocyte activation marker CDw137 when compared to B cells of healthy donors and non-type-A CVID patients. The lowered CD86 expression levels were found to correlate with reduced levels of CD86 mRNA. Since combined stimulation via B cell antigen receptor and CD40 cross-linking did not rescue the defects in CD86 and CDw137 expression, B cells of CVID type A patients resemble functionally unresponsive lymphocytes incapable of cooperating with T cells. The fact that these cells accumulate in type A CVID patients suggests a causal relationship with the pathogenesis of this disease.

CD95 expression and function on lymphocyte subpopulations in common variable immunodeficiency (CVID); related to increased apoptosis

Apoptosis is now recognized as a central process of development and disease, and it has been proposed as one of the mechanisms that may account for the lymphopenia seen in some diseases. In this study we measured spontaneous apoptosis and CD95 expression on different cell subpopulations from CVID patients, using flow cytometric techniques. We divided our patients into two groups according to their CD4+ and CD4+CD45RA+ cell counts. Our results clearly show increased spontaneous apoptosis and CD95 expression on the CD4+ and CD4+CD45RA+ subsets from lymphopenic CVID patients compared with normal subjects and disease controls. Interestingly, our lymphopenic CVID patients presented a profound reduction in absolute counts, mainly affecting the CD4+CD45RA+ subpopulation. We also found a statistically significant direct correlation between absolute numbers of CD4+CD45RA+ T cells and spontaneous apoptosis on the same subset in CVID patients, but attempts to induce CD95-mediated apoptosis were unsuccessful despite increased CD95 expression on CD4+ T cells. These findings suggest that apoptosis could be one of the mechanisms implicated in the significant lymphopenia present in these patients.

[Common variable immunodeficiency: one or multiple illnesses? 3 clinical cases]

Common variable immunodeficiency (CVID) is a major antibody-deficiency syndrome, associated with increased risk of bacterial infection, as well as autoimmune and granulomatous disease. The clinical and immunological features are heterogeneous. This heterogeneity is expressed by the case reports of three selected patients. These observations will be discussed, with reference to a recent classification of CVID distinguishing four different clinical entities: i) CVID presenting with clinical and immunological features of X-linked agammaglobulinemia; ii) CVID presenting with clinical and immunological features of X-linked hyper-IgM syndrome; iii) CVID associated with systemic granulomatous disease; and iiii) CVID associated with autoimmune manifestations.

Persistent activation of the tumor necrosis factor system in a subgroup of patients with common variable immunodeficiency--possible immunologic and clinical consequences

In patients with common variable immunodeficiency (CVI), we have previously defined a subgroup of patients (CVIHyper) characterized by decreased numbers of CD4+ lymphocytes in peripheral blood, splenomegaly, and persistent immune activation in vivo, particularly of monocytes/macrophages. To further characterize this hyperactivity, parameters of activation of the tumor necrosis factor (TNF) system (TNF alpha and soluble TNF receptors [sTNFRs]) were measured in 24 patients with CVI and 20 healthy controls. Patients with CVI had significantly higher serum levels of TNF alpha and both types of sTNFRs, with the highest levels in the CVIHyper subgroup. In vitro, peripheral blood mononuclear cells (PBMC) and purified monocytes from CVIHyper patients spontaneously released significantly higher levels, and, after lipopolysaccharide (LPS) stimulation, significantly lower levels of TNF alpha and soluble p75-TNFR than cells from both other CVI patients and healthy controls. CVIHyper patients also had significantly higher TNF alpha:sTNFRs ratios in both serum and in unstimulated PMBC supernatants. The present study demonstrates persistent in vivo activation of the TNF system in CVI, particularly in the CVIHyper subgroup. This activation may contribute to the pathogenesis of both clinical and immunologic manifestations in CVI.

On interleukins 4, 6 and 10 and their interrelationship with immunoglobulins G and M in common variable immunodeficiency

Following culture of human peripheral blood mononuclear cells (PBMNC) from 25 normal donors and 15 patients with common variable immunodeficiency (CVID), we were unable to identify any IL10-defective patients. Clear-cut effects of IL4 could be demonstrated in controls, while in CVID all effects are less pronounced. While in both controls and CVID baseline levels of IL6, IgG and IgM were found to be correlated, this was altered by the addition of either IL4 or Poke Weed Mitogen (PWM). We therefore conclude that the inability of PBMNC to produce IL10 is not the cause of CVID in our patients. In CVID, the regulating circuitry triggered by IL4 remains principally intact, however, some subgroups of CVID behave significantly differently.