Immunophenotypical alterations in a subset of patients with common variable immunodeficiency (CVID)

Interleukin-9 rescues class switching of Memory B cells derived from Common variable immunodeficiency patients

Impaired class switch memory (CSM) B cell formation is the hallmark of common variable immunodeficiency (CVID). Various T cell abnormalities have been observed in CVID patients indicating inadequate T-cell help to B cells. A major setback in understanding its pathogenesis is due to diverse clinical presentation. Therefore, we performed extensive immunological investigation in a cohort of CVID patients with similar clinical findings in order to unravel the T cell dysfunction and its influence on the defective humoral immune response. All recruited CVID patients exhibited B cells in the normal range, but reduced CSM B cells. However, patients showed reduced T cell proliferation, reduced level of serum Interleukin-9 (IL-9) and frequency of IL-9 expressing CD4 (Th-9) cells. IL-9 supplementation along with CD40 engagement was effective in inducing in vitro CSM B cells formation in CVID patients. Thus, IL-9 supplementation has the potential to restore impaired CSM B cell formation in CVID.

State-of-the-art diagnostic evaluation of common variable immunodeficiency

OBJECTIVE

To summarize the current understanding of diagnostic and postdiagnostic evaluation of common variable immunodeficiency (CVID).

DATA SOURCES

PubMed Central database.

STUDY SELECTIONS

Original research articles and review articles from 2015 to 2020 including seminal articles that shaped the diagnostic and postdiagnostic evaluation of CVID were incorporated. This work focuses on initial diagnosis of CVID, genetic evaluations, and postdiagnostic assessment of respiratory, gastrointestinal, and hepatobiliary diseases including spleen and lymph node enlargement.

RESULTS

CVID presents not only with frequent infections but also with noninfectious complications such as autoimmunity, gastrointestinal disease, chronic lung disease, granulomas, liver disease, lymphoid hyperplasia, splenomegaly, or malignancy. The risk of morbidity and mortality is higher in patients with CVID and noninfectious complications. Detailed diagnostic approaches, which may incorporate genetic testing, can aid characterization of individual CVID cases and shape treatment in some instances. Moreover, continued evaluation after CVID diagnosis is key to optimal management of this complex disorder. These postdiagnostic evaluations include pulmonary function testing, radiologic studies, and laboratory evaluations that may be conducted at frequencies determined by disease activity.

CONCLUSION

Although the diagnosis can be achieved similarly in all patients with CVID, those with noninfectious complications have distinct concerns during clinical evaluation. State-of-the-art workup of CVID with noninfectious complications typically includes genetic analysis, which may shape precision therapy, and thoughtful application of postdiagnostic tests that monitor the presence and progression of disease in the myriad of tissues that may be affected. Even with recent advancements, knowledge gaps in diagnosis, prognosis, and treatment of CVID persist, and continued research efforts are needed.

Laboratory Assays of Immune Cell Function in Immunodeficiencies

Laboratory assays of immune cell function are essential for understanding the type and function of immune defects. These assessments should be performed in conjunction with a detailed history and physical examination, which should guide the evaluation of patients with a suspected immune deficiency. Laboratory assays of immune cell function are critical for assessing and demonstrating the functional impact of genetic mutations. Advances in diagnostic techniques continue to expand the ability of clinicians and researchers to understand the complex immune pathophysiology that underlies these disorders.

Defective IL-4 signaling in T cells defines severe common variable immunodeficiency

Common variable immunodeficiency (CVID) is defined by hypogammaglobulinemia and B-cell dysfunction, with significant clinical and immunological heterogeneity. Severe non-infectious complications, such as autoimmunity, granulomatous disease and splenomegaly, constitute a major cause of morbidity in CVID patients. T cells are generally regarded important for development of these clinical features. However, while T-cell abnormalities have been found in CVID patients, functional characteristics of T cells corresponding to well-defined clinical subtypes have not been identified. As common γ-chain cytokines play important roles in survival and differentiation of T cells, characterization of their signaling pathways could reveal functional differences of clinical relevance. We characterized CVID T cells functionally by studies of cytokine-induced signaling, and correlated the findings to defined clinical subtypes. Peripheral blood T cells from 29 CVID patients and 19 healthy donors were analyzed for i) phenotype, ii) cytokine-induced (interleukin (IL)-2, IL-4, IL-7 and IL-21) phosphorylation of signal transducer and activator of transcription (STAT) 3, STAT5 and STAT6, and iii) T-helper (Th)1/Th2 polarization. Expression of IL-4 receptor and downstream signaling molecules was measured. A subgroup of CVID patients (n = 7) was identified by impaired IL-4-induced p-STAT6 in naive and memory CD4 and CD8 T cells. This corresponded to patients with the largest accumulation of severe (non-infectious) complications. The signaling defect persisted over years and was not due to constitutively activated p-STAT6. The CD4 T cells were strongly Th1-skewed, but IL-4 signaling was impaired independently of Th status. However, IL-4Rα and Janus kinase (JAK) 1 mRNA levels were significantly lower than in normal donors, providing a likely mechanism for the defective IL-4-induced p-STAT6 and Th1-bias. In conclusion, we identified a subgroup of CVID patients with defective IL-4 signaling in T cells, with severe clinical features of inflammation and autoimmunity.

T-cell abnormalities in common variable immunodeficiency: the hidden defect

This review discusses how the T-cell compartment in common variable immunodeficiency is marked by the premature arrest in thymic output, leading to T-cell exhaustion and immune dysregulation. Although B cells have been the main focus of the disorder, ample experimental data suggest that T-cell abnormalities can be seen in a large proportion of Freiburg Group 1a patients and those suffering from inflammatory complications. The reductions in T-cell receptor excision circles, naïve T cells, invariant NKT cells and regulatory T cells suggest a diminished thymic output, while CD8 T cells are driven towards exhaustion either via an antigen-dependent or an antigen-independent manner. The theoretical risk of anti-T-cell therapies is discussed, highlighting the need for an international effort in generating longitudinal data in addition to better-defined underlying molecular characterisation.

Large granular lymphocytes are universally increased in human, macaque, and feline lentiviral infection

Large granular lymphocytes (LGLs) have only been anecdotally reported in HIV infection. We previously reported an LGL lymphocytosis in FIV-infected cats associated with a rise in FIV proviral loads and a marked neutropenia that persisted during chronic infection. Extensive immunophenotyping of peripheral blood mononuclear cells in cats chronically infected with FIV were identified LGLs as CD8lo(+)FAS(+); this cell population expanded commensurate with viral load. CD8lo(+)FAS(+) cells expressed similar levels of interferon-γ compared to CD8lo(+)FAS(+) cells from FIV-naive control animals, yet CD3ɛ expression, which was increased on total CD8(+) T cells in FIV-infected cats, was decreased on CD8lo(+)FAS(+) cells. Down-modulation of CD3 expression was reversed after culturing PBMC for 3 days in culture with ConA/IL-2. We identified CD8lo(+)FAS(+) LGLs to be polyclonal T cells lacking CD56 expression. Blood smears from HIV-infected individuals and SIVmac239-infected rhesus macaques revealed increased LGLs compared to HIV/SIV negative counterparts. In humans, there was no correlation with viral load or treatment and in macaques the LGLs arose in acute SIV infection with increases in viremia. This is the first report describing and partially characterizing LGL lymphocytosis in association with lentiviral infections in three different species.

Laboratory diagnosis of primary immunodeficiencies

Primary immune deficiency disorders represent a highly heterogeneous group of disorders with an increased propensity to infections and other immune complications. A careful history to delineate the pattern of infectious organisms and other complications is important to guide the workup of these patients, but a focused laboratory evaluation is essential to the diagnosis of an underlying primary immunodeficiency. Initial workup of suspected immune deficiencies should include complete blood counts and serologic tests of immunoglobulin levels, vaccine titers, and complement levels, but these tests are often insufficient to make a diagnosis. Recent advancements in the understanding of the immune system have led to the development of novel immunologic assays to aid in the diagnosis of these disorders. Classically utilized to enumerate lymphocyte subsets, flow cytometric-based assays are increasingly utilized to test immune cell function (e.g., neutrophil oxidative burst, NK cytotoxicity), intracellular cytokine production (e.g., TH17 production), cellular signaling pathways (e.g., phosphor-STAT analysis), and protein expression (e.g., BTK, Foxp3). Genetic testing has similarly expanded greatly as more primary immune deficiencies are defined, and the use of mass sequencing technologies is leading to the identification of novel disorders. In order to utilize these complex assays in clinical care, one must have a firm understanding of the immunologic assay, how the results are interpreted, pitfalls in the assays, and how the test affects treatment decisions. This article will provide a systematic approach of the evaluation of a suspected primary immunodeficiency, as well as provide a comprehensive list of testing options and their results in the context of various disease processes.

Lung disease, T-cells and inflammation in common variable immunodeficiency disorders

INTRODUCTION

Besides hypogammaglobulinemia and recurrent infections, abnormalities of T-cells might contribute to lung damage in common variable immunodeficiency disorders (CVID).

MATERIALS AND METHODS

In 16 adult patients, the majority of whom had pulmonary abnormalities, we studied T-cell subsets and markers of inflammation in bronchoalveolar lavage fluid (BALF) and blood and their relations with pulmonary function and high resolution computed tomography (HRCT).

RESULTS

We demonstrated that some of the lymphocyte abnormalities previously demonstrated in peripheral blood from CVID patients, such as low CD4/CD8 T-cell ratio, were also present in BALF. Moreover, low BALF CD4/CD8 ratio (≤ 1), found in seven patients, was significantly associated with higher blood CD8⁺ cell count and to lower values of the lung function variables; forced expiratory volume (FVC), total lung capacity (TLC), vital capacity (VC) and residual volume (RV) in % of predicted. The expression of the inflammatory markers HLA-DR and CCR5 on T-cells was significantly higher, and the expression of CCR7 significantly lower, in BALF compared to blood, possibly reflecting an inflammatory/cytotoxic T-cell phenotype within pulmonary tissue in CVID. Furthermore, patients with bronchiectasis had higher concentrations of the pro-inflammatory cytokine TNFα in plasma, compared to those without.

CONCLUSION

Our findings suggest that inflammation and T-cell activation may be involved in the immunopathogenesis of pulmonary complications in 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.

Progressive multifocal leukoencephalopathy in a patient with common variable immunodeficiency and abnormal CD8+ T-cell subset distribution

BACKGROUND

Patients with primary hypogammaglobulinemia have been reported to have encephalopathy, but progressive multifocal leukoencephalopathy (PML) due to JC virus reactivation is a rare cause.

OBJECTIVE

To provide the clinical details and case discussion of a patient diagnosed as having common variable immunodeficiency (CVID) who has progressive neurodegenerative symptoms and was found to have PML and an abnormal CD8+ T-cell subset distribution.

METHODS

A detailed case report providing the patient's immunodeficiency history, diagnostic evaluation, and medical management and a review of related literature.

RESULTS

Before his neurodegenerative illness, the patient was found to have hypogammaglobulinemia, poor specific antibody responses, low circulating B-cell levels, and abnormal delayed-type hypersensitivity responses; there was no Bruton tyrosine kinase (BTK) mutation. The PML was diagnosed using brain biopsy and was confirmed using a DNA probe specific for JC virus. Peripheral blood flow cytometry at the time of PML diagnosis revealed an accumulation of naive CD8+ T cells (CD3+CD8+CD45RA+) and a deficiency of memory CD8+ T-cell subsets (CD3+CD8+CD45RA- or CD3+CD8+CD45RO+). Despite aggressive treatment with interleukin 2, interferon-gamma, and intravenous cidofovir, the patient died.

CONCLUSIONS

JC virus infection should be considered in the differential diagnosis of the patient with CVID and signs and symptoms of encephalopathy. The role of this patient's abnormal CD8' T-cell subset distribution in the development or control of this rare infection is worthy of consideration and has encouraged us to enumerate naive and memory CD4+ and CD8+ T-cell subsets in patients diagnosed as having CVID, even in the absence of neurodegenerative symptoms.

T and B lymphocyte subpopulations and activation/differentiation markers in patients with selective IgA deficiency

Selective deficiency of immunoglobulin A (IgAD) and common variable immunodeficiency (CVID) are genetically closely related diseases, both of unknown pathogenesis. A plethora of abnormalities in lymphocyte subpopulations and expression of activation markers were repeatedly documented in CVID patients, while almost no data are available about lymphocyte subpopulations in IgAD patients. We determined basic lymphocyte subpopulations and those subpopulations that were reported to be abnormal in CVID patients (CD25, human leucocyte antigen (HLA)-DR CD45RA, CD45RO, CD27, CD28 and CD29 on both CD4(+) and CD8(+) cells, CD57 and CD38 on CD8(+) cells, CD21, CD27, IgM, IgD on B lymphocytes) in 85 patients with IgAD, 47 patients with CVID and in 65 healthy controls. Statistical analysis was performed by the Mann-Whitney U-test; significant P-values were determined by means of Bonferoni's correction. Our results showed an increase in the relative number of CD8(+) cells and a decrease in the absolute number of CD4(+) cells compared to healthy people, but similar abnormalities in CVID patients were much more expressed. IgAD patients had significantly decreased expression of HLA-DR and increased expression of CD25 on CD4(+) lymphocytes, also CD29 expression was decreased on CD8(+) cells, while other activation/differentiation markers on T cells (including the expression of CD45RA and CD45RO antigens) were not changed. There were no statistically significant abnormalities in B lymphocyte developmental stages in IgAD patients compared to healthy controls. Our observation showed that the majority of T and B lymphocyte subpopulation abnormalities described previously in CVID are not present in IgAD patients.

Elevated levels of activated CD4 T cells in common variable immunodeficiency: association with clinical findings

BACKGROUND

Common variable immunodeficiency (CVID) is a very heterogeneous syndrome defined by impaired immunoglobulin production. The primary defect remains unknown, but many reports describe peripheral blood T and B lymphocyte dysfunctions in a substantial proportion of CVID patients. Immunophenotypic alterations on memory B lymphocytes correlate with clinical findings. A B-cell-oriented classification principle of the patients has been proposed.

METHODS AND RESULTS

We investigated the expression of activation surface molecules on CD4 and CD8 T-cells from 14 patients with CVID, 6 non-CVID hypogammaglobulinemic patients with recurrent infections, 47 asymptomatic HIV-positive patients without AIDS defining conditions and 23 healthy subjects. Lymphocyte subsets were analysed by three-colour flow cytometry. Monoclonal panel: CD38-FITC/HLADR-PE/CD4 or CD8-PerCP. In CVID patients serum levels of CD4 T-cells co-expressing the activation marker HLA-DR [CD4+DR+ (34 %), CD4+CD38+DR+ (18 %)] were significantly elevated compared with controls. Significant increases in CD8+DR+ (54%), CD8+ CD38+ (43%) and CD8+CD38+DR+ (29%) T-cells were observed in comparison with healthy controls. CVID patients with splenomegaly, lower pre-infusion IgG levels (< 600 mg/dl), autoimmune or lymphoproliferative conditions demonstrated even higher levels of CD4+CD38+DR+T cells (22, 22, 21 and 21% respectively) compared with other CVID patients (13, 13, 15 and 15% respectively).

CONCLUSION

These findings indicate a state of ongoing T lymphocyte activation which is associated with clinical findings frequently observed in CVID.

Costimulatory molecules and cytokine production by T lymphocytes in common variable immunodeficiency disease

Common variable immunodeficiency (CVID) is a heterogeneous syndrome characterized by hypogammaglobulinaemia and recurrent infections. Although early works pointed to a primary B-lymphocyte defect as a cause of the disease, a failure in T-lymphocyte cooperation has also been suggested. T cells exert their costimulatory function through either membrane costimulatory molecules or secreted cytokines, both having an influence in the development of the humoral response. The aim of our study was to evaluate whether an abnormal expression and induction of costimulatory molecules or alterations in the production of cytokines by T cells cause deficient T/B cooperation in CVID patients. We studied the expression and upregulation of costimulatory molecules (CD28, CD40L/CD154 and CTLA-4/CD152) and production of cytokines (IL-2, IL-4, IL-6, IL-10, IFN-gamma and TNF-alpha) in purified T lymphocytes from CVID patients stimulated with optimal doses of anti-CD3 or suboptimal doses of anti-CD3 and anti-CD28. Stimulated T cells from CVID patients expressed normal levels of CD28, CD40L/CD154 and CTLA-4/CD152 when compared with controls. Except for higher production of IL-4 after stimulation with anti-CD3, T cells of CVID patients produced similar amounts of cytokines compared with controls. An imbalance between costimulatory molecules expression (CD28, CD40L/CD154 and CTLA-4/CD152) and cytokine production by T cells does not explain a deficient cooperation between T and B cells in this group of CVID patients.

Polyclonal expansion of large granular lymphocytes in common variable immunodeficiency - association with neutropenia

Common variable immunodeficiency (CVID) is the most frequent symptomatic primary immunodeficiency disease, characterized by low levels of circulating immunoglobulins and recurrent bacterial infections, particularly of the respiratory tract. T cell dysfunction is often present, and lymphoproliferative and autoimmune disorders as well as haematological cytopenias are frequently observed. In this study, we report a polyclonal expansion of large granular lymphocytes (LGL) in a substantial proportion of CVID patients, associated with splenomegaly, increased numbers of CD8(+) T cells, inverted CD4 : CD8 T cell ratios and neutropenia. CVID patients who had both increased numbers of LGL and granulocytopenia had elevated levels of soluble Fas ligand (sFasL). Our observations indicate that CVID may be added to the list of inflammatory diseases associated with increased numbers of LGL. Furthermore, our findings suggest common pathogenic mechanisms of granulocytopenia in CVID and lymphoproliferative disease of granular lymphocytes.

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.

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.

Gene expression analysis of peripheral T cells in a subgroup of common variable immunodeficiency shows predominance of CCR7(-) effector-memory T cells

Common variable immunodeficiency (CVID) represents a heterogeneous group of antibody deficiency syndromes, characterized by defective antibody production in which T cell deficiency may play a pathogenic role. A subgroup of CVID patients has impaired in vitro T cell proliferation. Using microarray analyses of T cells from these patients, we found a gene expression pattern different from healthy controls and patients with X-linked agammaglobulinaemia. The profile of the differentially expressed genes suggests enhanced cytotoxic effector functions, antigen experienced or chronically activated T cells and a predominance of CCR7(-) T cells. Further experiments using flow cytometry revealed a striking predominance of CCR7(-) T cells in a subgroup of CVID patients, and an association with impaired T cell proliferation. Our observations indicate that a predominance of CCR7(-) T cells with effector-memory cell features and with reduced proliferative capacity may characterize a subgroup of CVID.

The genetics of hypogammaglobulinemia

Etiologies for human hypogammaglobulinemias are diverse and include genetic and nongenetic causes. Although recent reviews focus on the complex genetics of common variable immunodeficiency, in this review, we survey different causes of hypogammaglobulinemias and discuss possible mechanisms.

The Complex Genetics of Common Variable Immunodeficiency

Immunoglobulin (lg)A deficiency and common variable immunodeficiency (CVID) are the most common primary immunodeficiency disorders in North America and Europe. These diseases appear to comprise a familial spectrum of immunodeficiency that ranges from partial IgA deficiency to a complete absence of serum immunoglobulin. The CVID phenotype is typically acquired and can spontaneously revert to IgG and IgM sufficiency. Family studies suggest the presence of at least two susceptibility loci within the major histocompatibility complex on the short arm of chromosome 6: one located near the class II region and the other located near the junction between the class III and class I regions. Inheritance of these susceptibility genes may yield an additive risk for the development of immunodeficiency. First-degree family members of patients with CVID are at risk throughout their lives for the development of these diseases and should be monitored with a high index of suspicion.

Lymphomas of mucosal-associated lymphoid tissue in common variable immunodeficiency

Common variable immunodeficiency (CVID) is a primary immunodeficiency disease characterized by low serum immunoglobulins IgG, IgA, and usually IgM. The central immune deficiency is impaired secretion of immunoglobulins and lack of antibody production; however, T cell dysfunction and a variety of inflammatory complications suggest global immune dysregulation. A number of reports have documented the association of primary immunodeficiency diseases with the development of non-Hodgkin's lymphoma (NHL). In CVID, the risk has been estimated to lie between 1.4% and 7%. As for NHL arising in other immunodeficiency states, the lymphomas in CVID are extranodal and are usually B cell in type. Of 22 B cell lymphomas that have appeared over a period of 25 years in a cohort of subjects with CVID, five lymphomas, appearing in more recently studied subjects, that arose in mucosal sites would be classified as mucosa-associated lymphoid tissue (MALT) lymphomas. MALT lymphomas are low-grade B cell lymphomas that result from a proliferation of neoplastic marginal-zone related cells of lymphoid tissue and tend to occur in organs that have acquired lymphoid tissue due to long-term infectious or autoimmune stimulation. Lymphomas of this kind have not been described in patients with congenital immunodeficiency, although chronic mucosal antigen stimulation is an integral part of these immune deficiency states.

Enhanced T cell apoptosis in common variable immunodeficiency: negative role of the fas/fasligand system and of the Bcl-2 family proteins and possible role of TNF-RS

CVI is a primary immunodeficiency characterized by a failure of B cell differentiation associated with an array of T cell defects, such as enhanced T cell apoptosis. In this study we investigated the mechanisms underlying CVI enhanced T cell death. We analysed both the expression of Fas using flow cytometry techniques and the expression of FasL mRNA using RT-PCR in CVI T cells. We could not find any significant differences between CVI and normal subjects with regard to Fas expression, although there was a subgroup of CVI patients with very high Fas expression which was accompanied by an up-regulation of FasL mRNA. However, attempts to induce Fas-mediated apoptosis in these high Fas expressing cells, as evaluated by propidium iodide staining and APO2.7 staining, were unsuccessful. We also investigated intracellular levels of Bcl-2, bcl-xl and bax in CD4(+) and CD8(+) CVI T cells, as well as the bax/Bcl-2 ratio, using flow cytometry techniques but could not detect any differences between CVI and normal subjects. Finally we analysed TNF-RI and TNF-RII mRNA expression in CD4(+) and CD8(+) CVI T cells using semiquantitative RT-PCR and found a significant increase in expression of both TNF-Rs in CD4(+) T cells from CVI patients. Our data suggest that the increased expression of both TNF-Rs on T cells may be one of the mechanisms responsible for the accelerated T cell apoptosis in CVI.

Deficiency in circulating natural killer (NK) cell subsets in common variable immunodeficiency and X-linked agammaglobulinaemia

Absolute and relative NK cell numbers were determined in peripheral whole blood by flow cytometry in patients with common variable immunodeficiency (CVID) (n = 55) and X-linked agammaglobulinaemia (XLA) (n = 19) on regular immunoglobulin (IVIG) therapy. Absolute CD3-CD16+ NK cell numbers were significantly reduced in CVID patients (median 108/microl, range 23-815), compared with normal subjects (n = 60) (289/microl, range 56-640, P < 0.001). Total lymphocyte concentrations were significantly lower in CVID (median 1587/microl, range 523-7519) compared with normal subjects (median 2019/microl, range 1124-3149, P = 0.004), with the percentage of NK cells also being significantly decreased (median 7.5%, range 3.0-33. 0%, compared with 14.2%, range 2.6-30.8%, P < 0.001). In XLA, absolute NK cell numbers (median 140/microl, range 32-551, P < 0. 001) but not relative numbers were significantly reduced compared with normal controls. We excluded the possibility that IVIG interferes with in vitro binding of CD16 MoAbs. Further analysis of NK cell subsets showed a deficiency of both CD16+ and CD56+ cells in CVID, most marked in the CD3-CD8dim subpopulation, which may be due to increased homing of these cells to the gut. Serial studies on a small number of patients suggest that IVIG therapy has no short-term effect on NK cells, although we cannot exclude an effect with prolonged use. Although there are no obvious clinical effects of the NK depletion in CVID and XLA, this may be a factor in their predisposition to cancer.

Enhanced apoptosis of T cells in common variable immunodeficiency (CVID): role of defective CD28 co-stimulation

CVID is a primary immune disorder in which hypogammaglobulinaemia may be associated with a number of T cell defects including lymphopenia, anergy, impaired lymphocyte proliferation and deficient cytokine secretion. In this study we show that T cells of CVID subjects, in comparison with control T cells, undergo spontaneous apoptosis in culture and markedly accelerated apoptosis after gamma-irradiation. Although costimulation of the CD28 receptor following engagement of the TCR/CD3 receptor normally provides a second signal necessary for IL-2 secretion, CD28 costimulation in CVID does not significantly increase IL-2 production, nor does this combination of activators enhance the survival of irradiated CVID T cells, as it does for cultured normal T cells. Addition of IL-2 enhances CVID T cell survival, suggesting that the IL-2 signalling pathways are normal. CVID T cells have similar expression of Bcl-2 to control T cells. CD3 stimulation up-regulates T cell expression of bcl-xL mRNA for normal T cells, but anti-CD28 does not augment bcl-xL expression for CVID subjects with accelerated apoptosis. Defects of the CD28 receptor pathway, leading to cytokine deprivation and dysregulation of bcl-xL, could lead to poor T cell viability and some of the cellular defects observed in CVID.

Identification of a subset of common variable immunodeficiency patients with impaired B-cell protein tyrosine phosphorylation

The mechanisms responsible for common variable immunodeficiency syndrome (CVID) are as yet unknown. In the present study, we show that the B-cell dysfunction in a subset of CVID patients is caused by defective protein tyrosine phosphorylation (PTP). We demonstrated that the PTP level and immunoglobulin (Ig) secretion malfunctions can be successfully repaired when normal plasma membrane components are implanted into these patients' B cells. Stimulation of CVID patients' peripheral blood mononucleated cells with anti-Ig antibody revealed that 7 of 11 patients had lower PTP levels than those found in the normal donor cells. Plasma membrane implantation to the cells of these patients resulted in elevated PTP levels which reached normal levels upon stimulation with anti-human Ig antibody. The results revealed two distinct groups of CVID patients. The first group included patients whose B cells expressed low PTP levels after Ig stimulation. In these patients the plasma membrane implantation restored the normal PTP level as well as the ability to secrete IgM and/or IgG after B-cell stimulation. In the second group, patients whose B cells expressed a normal PTP level after Ig stimulation, with no restoration of their ability to secrete Ig upon plasma membrane implantation and lipopolysaccharide stimulation. We conclude that the first group has an early signal transduction defect located in the B-cell plasma membrane, while in the second group the defect is located elsewhere.

Nef protein induces differential effects in CD8+ cells from HIV-1-infected patients

BACKGROUND

The Nef protein of HIV-1 is suspected to play a role in the depletion of uninfected CD4+ lymphocytes that leads to AIDS. By contrast its effect on CD8+ cells, whose functions are also deregulated during HIV-1 infection, is presently unclear. Here we describe a number of derangements induced in vitro by Nef in CD8+ cells from HIV-1-infected patients.

DESIGN

Peripheral lymphocytes from 16 HIV-1+ subjects and 9 uninfected individuals were cultivated on a Nef-transfected mouse fibroblast layer exposing the carboxyl-terminal region of the viral protein on cell membrane. The cultures were then measured for both apoptosis and proliferation by subdiploid DNA content and Ki67 expression, respectively, whereas the molecular analysis of purified CD8+ cells investigated the Fas-L mRNA levels in Nef-treated CTLs. In addition, we evaluated the Nef-induced variation in the extent of CD8+/HLA-DR+ subset, which includes non cytotoxic cells secreting T-cell antiviral factor (CAF) and a soluble factor inhibiting the HIV-1 replication.

RESULTS

The viral protein induced in peripheral blood lymphocytes (PBL) a moderate tendency to proliferate, as measured by the increment of Ki67 antigen, particularly on the CD8+ subset of HIV-1 infected individuals (P < 0.05). This profile was particularly evident in cultures from patients with severe CD4+ lymphopenia and paralleled an apparent expansion of the CD8+/CD57+ suppressor cell subset. Molecular analysis of purified CD8+ cells revealed a defective expression of Fas-L mRNA in Nef-cultured CTLs, whereas the viral protein exerted a down modulatory effect on the CD8+/HLA-DR+ subset (P < 0.05), thus suggesting a potential inhibition of CAF.

CONCLUSIONS

These results support a potential role of Nef in the progression of HIV-1 infection as a number of cellular functions are affected in the CD8+ subset. In particular, the defective functions of CD8+ cells induced by the viral protein could contribute, at least partly, to the escape of HIV-1 from the immune control of these cells.

A double-blind, placebo-controlled, crossover therapy study with natural human IL-2 (nhuIL-2) in combination with regular intravenous gammaglobulin (IVIG) infusions in 10 patients with common variable immunodeficiency (CVID)

Ten CVID patients with defective IL-2 synthesis in vitro were treated with nhuIL-2 in a placebo-controlled, double blind, crossover therapy study during a period of 12 months. No severe side-effects of nhuIL-2 were recorded. Marginal serum nhuIL-2 levels were measurable in individual patients only during the therapy phase. Serum levels of soluble IL-2 receptors were unaffected by the therapy. nhuIL-2 and placebo groups did not differ significantly with respect to requirement of IVIG substitutions which were performed whenever serum IgG levels dropped below 5 g/l: a total of 53 IVIG infusions (corresponding to 17.6 g IgG/month per patient) was necessary during the placebo phase, and 48 infusions (16.4 g IgG/month per patient) during the nhuIL-2 treatment phase. Thus, nhuIL-2 therapy was ineffective in improving spontaneous IgG synthesis in vivo. Nevertheless, the group of patients receiving nhuIL-2 during the first 6 months of the study exhibited a significant reduction of severe infections (n = 25) during the following 6 months of placebo treatment (n = 7) (P<0.045). The infection score dropped in this group from 181 to 23 (P<0.015). Patients of the second group receiving first placebo and then nhuIL-2 did not experience a significant difference in number and score of infectious episodes: 25 infections were recorded during the first 6 months and 24 during the following 6 months. We suppose that nhuIL-2 therapy of CVID patients reduces susceptibility to severe infections, possibly via the induction of a specific antibody response, which is effective at the earliest 6 months after initiating nhuIL-2 therapy.

Humoral and cellular immune response to elastin in patients with systemic sclerosis

The humoral immune response against elastin and collagen was studied in parallel with the delayed type hypersensitivity (DTH) reaction to elastin and the percentage of lymphocyte subpopulations in peripheral blood in 20 patients with systemic sclerosis (SSc). An increase of anti-elastin antibodies of all subclasses was found with a significant prevalence of IgE and IgA antibodies. The profile of anti-collagen type I and type IV antibodies showed an increase of IgE isotypes. In 25% of the patients (5 out of 20) positive DTH reactions to elastin were observed as compared to the negative skin reactions in all control individuals. At the same time a significant hyporeactivity to common bacterial and mould antigens was found in 40% of the patients (versus 16% in the control group) which could be an explanation for the low incidence of positive anti-elastin DTH reaction. The DTH hyporeactivity in SSc cases was in contrast with the increased percentage of CD4 T cells (58.4 vs. 42.0) and increased CD4/CD8 ratio (2.5 vs. 1.5) in the peripheral blood of the patients. This finding together with the increased IgE antibodies to elastin and collagen type I and type IV might suggest a possible shift of the immune balance towards the Th2 type of immune response. This is in line with the increased CD8+CD57+ cells which correlated with the highest number of other parameters studied - disease duration, total skin score, IgE anti-elastin antibodies, IgG anti-collagen type I antibodies, CD4/CD8 ratio and CD19 B cells. The results of this study demonstrated the existence of both humoral and cell-mediated immune response against elastin in SSc patients. However, we could not define whether this was an essential part of pathogenetic mechanisms or a secondary phenomenon reflecting the extent of the damage of connective tissue.

Common variable immunodeficiency with CD4+ T lymphocytopenia and overproduction of soluble IL-2 receptor associated with Turner's syndrome and dorsal kyphoscoliosis

An unusual combination of common variable immunodeficiency (CVID) and Turner's syndrome in a Saudi woman aged 20 years is presented. In addition to panhypogammaglobulinaemia, the patient had CD4+ T lymphocytopenia; however, there was evidence of in vivo activation of T cells and overproduction of soluble interleukin 2 receptor in culture supernate. Mantoux test was positive, but lymphoblastic response to non-specific mitogen was impaired. Immunogenetically the patient was HLA-DR3 positive and karyotypically she was a mosaic (45XO/46XX) with ring X chromosome (46Xr(X)). The presence of severe kyphoscoliosis was possibly related to ring X chromosome. This case highlights the grave consequences of the delayed diagnosis of immunodeficiency and emphasises the heterogeneous nature of CVID.

Human cytomegalovirus infection is not increased in common variable immunodeficiency

It has been postulated that human cytomegalovirus (HCMV) infection may have a role in the pathogenesis of common variable immunodeficiency (CVID). Many patients have a lymphocyte phenotype similar to that seen in HCMV infection, HCMV mononucleosis may precipitate hypogammaglobulinaemia, and a previous small study of common variable immunodeficient patients reported a high rate of active HCMV infection. This study investigated the presence and activity of HCMV infection in 102 CVID patients. Buffy coats were examined for the presence of HCMV IE and glycoprotein B genes using highly sensitive nested PCR. 30 blood donors of known HCMV serologic status were used as controls. There was no significant difference in HCMV positivity by PCR between patients and controls. Enrichment for mononuclear cells prior to PCR had no effect on sensitivity. Twenty-five patients were also examined for HCMV antigenaemia by staining buffy coat cytospins with monoclonal antibodies directed against the HCMV pp65 lower matrix protein, a technique widely used for diagnosis of active HCMV disease. Only one patient was positive (and also positive by PCR). Whilst these results do not exclude prior infection contributing to antibody deficiency in a small proportion of CVID patients, this study refutes the previously reported increase in active HCMV infection in CVID.

Analysis of a family containing three members with common variable immunodeficiency

BACKGROUND

Common variable immunodeficiency (CVID), a diverse immunodeficiency syndrome characterized by low immune globulin levels and recurrent infections, has been observed in families with the HLA A1 B8 DR3 haplotype.

METHODS

We report a two-generation family with three members affected by CVID. Immunoglobulin levels, antibody titers, lymphocyte marker analyses, T cell proliferation assays, and HLA typing were performed on the affected family members.

RESULTS

Studies of the affected patients revealed low levels of immunoglobulin G and A; normal tetanus, rubella and rubeola antibody titers; low B cell numbers; normal T cell numbers; normal CD4/CD8 ratios and normal lymphocyte proliferation studies. HLA typing did not reveal the HLA A1 B8 DR3 haplotype previously associated with familial CVID.

CONCLUSION

We report a family with a unique presentation of CVID involving possible genetic inheritance other than the HLA A1 B8 DR3 haplotype and possessing lymphocyte characteristics distinct from those usually seen in sporadic CVID.

B cells from a distinct subset of patients with common variable immunodeficiency (CVID) have increased CD95 (Apo-1/fas), diminished CD38 expression, and undergo enhanced apoptosis

We investigated the role of apoptosis in the differentiation failure of B cells from a selected subpopulation of patients with CVID delineated by B cell surface marker analysis, in vitro IgE response, and molecular markers of B cell VH gene repertoire. These patients had altered display of B cell surface molecules that play a role in apoptosis. The patients' B cells had a 4.5-250-fold increase in CD95 (Apo-1, fas) expression and increased CD95 display on their T cells. CD38, a molecule important in preventing germinal centre B cell apoptosis, was reduced on the patients' B cells. The expression of this molecule was inducible on the CVID lymphocytes with retinoic acid. Increased spontaneous apoptosis in vitro was observed with the patients' B (23%) and T cells (10%) compared with normal cells (13% and 3%, respectively). Stimulation in vitro with IL-4 and CD40 rescued the B cells from apoptosis and allowed for their differentiation. However, IL-4 plus alpha CD40-driven immunoglobulin production was not quantitatively or qualitatively normal. Failure to overcome apoptosis, a normal step in germinal centre B cell development, may be involved in the lack of differentiation seen in this subset of CVID patients.

Common variable immunodeficiency: clinical aspects and recent progress in identifying the immunological defect(s)

Common variable immunodeficiency (CVID) comprises a heterogeneous group of patients with as yet undefined genetic defects. Patients with CVID have in common a decrease in the levels of one or more serum immunoglobulin isotypes and a severe defect in the production of specific antibodies. Typically, the patients suffer from recurrent infections of the upper and lower respiratory tract or the gastrointestinal tract. In consequence of these infections patients may develop severe organ damage, such as chronic pulmonary disease with bronchiectases, leading to pulmonary failure. Early diagnosis of CVID is important, as antibody deficiency can efficiently be treated by regular intravenous IgG (IVIG) substitution therapy. IVIG therapy prevents the occurrence of further acute infectious episodes and the development of long-term complications. The basic immunological defect(s) in patients with CVID are still unknown. There is currently no convincing evidence for an intrinsic B-cell defect in patients with CVID. A defect in T-cell activation due to impaired signal transduction upon T-cell receptor triggering has been described in a large subgroup of patients with CVID. Defective T-cell activation may lead to an impairment in cognate T-B-cell interaction due to impaired expression of CD40 ligand and/or abnormalities in the production T-cell-derived cytokines required for fully functional B-cell activation, proliferation and/or differentiation which could indeed explain the impairment in antibody production present in CVID patients.

Common variable immunodeficiency (CVID) and MxA-protein expression in blood leucocytes

The underlying immunopathogenic mechanism of CVID has been suspected to involve a chronic viral infection or an autoimmune condition. However, formal proof of viral infection is lacking. Measurement of MxA-protein in leucocyte lysates is a sensitive test for evaluating the activation of the host's interferon system. Both viral infections and autoimmune diseases such as systemic lupus erythematosus (SLE) strongly induce MxA-protein in peripheral leucocytes. We therefore examined 15 patients with longlasting hypogammaglobulinaemia for MxA-protein induction in vivo: 13 patients suffered from CVID, one from hyper-IgM syndrome, and one patient had chronic B lymphocytic leukaemia associated with immunoglobulin deficiency and chronic papilloma virus infection (condylomata accuminata). Only the latter patient exhibited a strong MxA-protein expression; two CVID patients were borderline positive, and the remaining 12 patients including the hyper-IgM syndrome were MxA-protein-negative. There was no relationship between MxA expression and low CD4/CD8 ratios or increased CD8/CD57+ T cell counts, although both conditions are often observed in CVID as well as in chronic viral infections. When exposed in vitro to interferon-alpha (IFN-alpha), peripheral blood leucocytes of four MxA-negative patients were capable of producing normal amounts of MxA-protein. Taken together, these results argue against a viral or autoimmune pathogenesis of CVID.

Common variable immunodeficiency and inclusion body myositis: a distinct myopathy mediated by natural killer cells

Inclusion body myositis developed in two men, 36 and 48 years old with long-standing common variable immunodeficiency. Immunophenotypic analysis of the endomysial cells showed an increased number of natural killer (NK) cells (defined as CD57+, CD56+, CD3-, CD8-, CD68-) accounting for 8.5 to 9.5% of the total cells, compared with a mean of 1% in sporadic inclusion body myositis. The remaining cells were CD8+, macrophages, and CD4+ T cells. NK cells were positive for intercellular cell adhesion molecule-1 and invaded muscle fibers negative for major histocompatibility complex (MHC) class I. In contrast to ubiquitous endomysial expression of MHC class I antigen in sporadic inclusion body myositis, the MHC class I in common variable immunodeficiency and inclusion body myositis was absent or weakly expressed in only some of the muscle fibers surrounded by CD8+ cells. Enteroviral or retroviral RNA sequences were not amplified. Treatment with intravenous immunoglobulin improved strength in 1 patient whose repeated muscle biopsy specimen showed normal NK cells. We conclude that inclusion body myositis can develop in patients with common variable immunodeficiency. Common variable immunodeficiency with inclusion body myositis is an immune myopathy mediated by NK cells in a non-MHC class I-restricted cytotoxicity, and by CD8+ cells in an MHC class I-restricted process. This is the first description of an inflammatory myopathy in which NK cells participate in the myocytotoxic process.

Evaluation of the child with suspected primary immunodeficiency

Infections are one of the major causes for visits to paediatricians. Most children recover without sequelae, untreated or if treated properly, and develop specific immunity towards the challenging microorganisms (mostly viruses). There is a small proportion of children however, with unusual frequent, severe, chronic, recurrent or opportunistic infections in whom an underlying immunodeficiency must be suspected. Based on current knowledge about the major types of congenital immunodeficiencies this review suggests a diagnostic approach to these children. Early evaluation will allow early identification of affected children and, subsequently, lead to proper treatment before devastating infections cause irreversible organ damage.

Activated CD4+ and CD8+ T-cell subsets in Wegener's granulomatosis

Several lines of evidence argue in favour of an involvement of T cells in the pathogenesis of Wegener's granulomatosis (WG). These include the presence of highly specific IgG autoantibodies to proteinase 3, perivascular T-cell infiltrates and elevated amounts of soluble interleukin-2 (IL-2) receptors in patient's serum. In order to further address this question we evaluated by double immunofluorescence and flow cytometry the expression of several cell surface molecules associated with T-cell activation. As compared to healthy controls (n = 15), the CD4+ subset was significantly diminished, while the percentage of CD8+ T cells was elevated in WG patients (n = 24). Within the CD4+ T-cell subset we found a highly significant increase in activation/memory markers (CD25, CD29, HLA-DR). Within the CD8+ T-cell subset the expression of CD11b, CD29 and CD57 was significantly elevated, while the expression of VD28 was reduced. The use of 10 V beta-, 1 V alpha- and 1 V gamma-specific monoclonal reagents failed to reveal any significant bias in the peripheral T-cell receptor V-gene repertoire of WG patients. There was also no correlation between T-cell activation markers and laboratory parameters [C-reactive protein (CRP), ESR], disease duration or therapy. A significant correlation was found only for the degree of organ involvement and the increase in CD4+ T cells coexpressing HLA-DR, as well as the increase in CD57 expression on CD8+ T cells. In conclusion, both CD4+ and CD8+ T-cell subsets were activated in WG. Cytotoxic CD8+CD57+CD11b+CD28- T cells may directly contribute to damage of vascular endothelium.

A case of common variable immunodeficiency associated with cyclic thrombocytopenia

A 12 year old boy was found to be deficient in immunoglobulins (Ig) A, G2 and G4, and common variable immunodeficiency was diagnosed. He also had cyclic thrombocytopenia at intervals of approximately 28-30 days. His bone marrow revealed normocellular with slightly decreased megakaryocytes. In vitro colony assays showed markedly imparied megakaryocytopoiesis, erythropoiesis and granulopoiesis. Platelet-associated IgG was elevated at his thrombocytopenic phase. Direct Coombs' test was repeatedly positive. Although not defined at present, we suggest the autoimmune nature of the disease.

The costimulatory signal CD28 is fully functional but cannot correct the impaired antigen response in T cells of patients with common variable immunodeficiency

A wide spectrum of different immunologic abnormalities have been postulated as being responsible for the impairment of specific antibody production and the decrease in all or selected immunoglobulin isotypes present in common variable immunodeficiency (CVID). These abnormalities include impaired B cell differentiation and/or function, defective macrophage function, and significant T cell defects. The aim of the present study was to delineate whether the accessory molecule CD28 is involved in the impaired antigen response of T cells from patients with CVID. Our results demonstrate that CD28 costimulation was functional in T cells stimulated with anti-CD3 or anti-TCR MoAb, but could not correct the impaired response of patients' peripheral blood T cells to tetanus toxoid. Analysis of patients' long-term cultured T cells further confirmed these results. Exogenous rIL-2, another costimulus, augmented but did not correct the defective proliferation and lymphokine production in patients' antigen-driven peripheral blood T lymphocytes or in long-term cultured T cells. These findings indicate that the CD28 signalling pathway in these patients' T cells is unimpaired, and that costimulation via CD28 cannot correct the defect occurring in the course of TCR-mediated T cell activation.

Intestinal B cell defects in common variable immunodeficiency

The humoral immune system of the small intestine of 17 patients with common variable immunodeficiency (CVID) was studied by immunohistology using antibodies specific for IgA1,2, IgM, IgG1-4, the J chain and the secretory component (SC). IgA1,2+, IgG2+ and IgM+ lamina propria B cells were totally lacking in 65% (11/17), 41% (7/17) and 18% (3/17) of CVID patients, respectively. One patient exhibited an isolated IgA1 subclass deficiency. The proportion of plasma cells in conventionally stained histological sections of the same intestinal biopsies showed a close correlation with the numbers of IgA+ and IgM+ cells. Considerable numbers of J chain-synthesizing cells were present in all patients with CVID, indicating the presence of early B cells unable to differentiate into immunoglobulin-producing plasma cells. Most of the patients with intestinal IgA and/or IgM defects strongly expressed the SC in their enterocytes, suggesting an immunoglobulin-independent regulation of the SC. Clinically, only CVID patients with intestinal IgA defects developed intestinal infections with Giardia lamblia, Campylobacter jejuni or Candida albicans. The outcome of in vitro immunoglobulin synthesis assays with peripheral blood lymphocytes did not predict the presence or absence of the respective isotype-producing B cells in the intestinal lamina propria. Thus, immunohistological examinations of intestinal biopsies are required to determine the extent of mucosal immunodeficiency in CVID patients.

Long-term administration of 13-cis retinoic acid in common variable immunodeficiency: circulating interleukin-6 levels, B-cell surface molecule display, and in vitro and in vivo B-cell antibody production

We have previously shown that retinoids can induce differentiation of B cells in vitro as well as in vivo in patients with common variable immunodeficiency (CVI). While changes were observed over 1 week when retinoic acid (RA) was added to CVI hybridoma cells in vitro, maturation of the patients' B-cell compartment in vivo occurred only after 4 months of drug administration. We have now performed a 64-week open trial of oral 13-cis RA in five patients to see if prolonged treatment would result in continued improvement in their humoral immune compartment. In this trial, drug was given for 32 weeks followed by a 32-week wash-out period. During the treatment, the patients showed changes in a variety of parameters indicating an alteration towards normal of their humoral immune systems. This change included a fall in the elevated circulating interleukin-6 (IL-6) levels, a more normal display of B-cell surface markers (L-selectin and CD20), a decrease in B-cell size, and improved in vitro and in vivo B-cell function. In order to determine if VH gene use was affected by the retinoid treatment, VH gene expression in the CVI patients was characterized. Results showed an unusual predominance of non-mutated VH gene sequences, representative of cells that are recent bone marrow emigrants. While no common pattern of change occurred in VH gene segment use in the patients while on retinoid therapy, large-scale (> 10-fold) changes in the expression of these genes were observed in each individual over time. Taken together, these results provide multiple lines of evidence that 13-cis RA promotes maturation of B cells in patients with CVI. However, the effect appears to be partial, such that stimuli in addition to 13-cis RA will be necessary to provide for further B-cell differentiation in order to achieve normalization of humoral immunity.

Increased expression of CD25 and adhesion molecules on peripheral blood lymphocytes of patients with Wegener's granulomatosis (WG) and ANCA positive vasculitides

Peripheral blood lymphocytes of 29 c-ANCA positive WG patients fulfilling the ACR classification criteria were examined for the expression of various leukocyte surface molecules by dual marker cytofluorometry (FACStar, Becton Dickinson). Activation markers such as CD25, HLA-DR, CD29 and adhesion molecules (ICAM-1 and LFA-3) were clearly elevated in this group in comparison to 40 healthy volunteers. Similar results were obtained for p-ANCA positives vasculitides (n = 13) and, unexpectedly, also for patients suffering from cholesteatoma, a chronic, bacterial infection of the middle ear (n = 21). The results are discussed in view of a pathogenic model for WG and vasculitic disorders.