Impaired selective cytokine production by CD4+ T cells in Common Variable Immunodeficiency associated with the absence of memory B cells

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.

Members of the Regulatory Lymphocyte Club in Common Variable Immunodeficiency

The role of CD4 T regulatory cells is well established in peripheral tolerance and the pathogenesis of the murine model and human autoimmune diseases. CD4 T regulatory cells (CD4 Tregs) have been investigated in common variable immunodeficiency (CVID). Recently, additional members have been added to the club of regulatory lymphocytes. These include CD8 T regulatory (CD8 Tregs), B regulatory (Bregs), and T follicular helper regulatory (T_FR) cells. There are accumulating data to suggest their roles in both human and experimental models of autoimmune disease. Their phenotypic characterization and mechanisms of immunoregulation are evolving. Patients with CVID may present or are associated with an increased frequency of autoimmunity and autoimmune diseases. In this review, we have primarily focused on the characteristics of CD4 Tregs and new players of the regulatory club and their changes in patients with CVID in relation to autoimmunity and emphasized the complexity of interplay among various regulatory lymphocytes. We suggest future careful investigations of phenotypic and functional regulatory lymphocytes in a large cohort of phenotypic and genotypically defined CVID patients to define their role in the pathogenesis of CVID and autoimmunity associated with CVID.

[Common variable immune deficiency in adult patients: analysis of 13 cases and literature review]

OBJECTIVE

To investigate the clinical and immunological characteristics, treatment and prognosis of common variable immune deficiency (CVID) in adult patients.

METHODS

We retrospectively analyzed the clinical data of 13 adult patients hospitalized in our hospital for CVID diagnosed according to the criteria in International Consensus Document (2016), and analyzed their clinical manifestations, laboratory test results, imaging findings, pathological examinations and treatments.

RESULTS

The mean age of onset was 24.46±16.82 years in these patients, who had a mean age of 32.54±14.86 years at diagnosis with a median diagnostic delay of 5 years (IQR: 2-15 years). The main manifestation of the patients was repeated infections, including repeated respiratory tract infection (10 cases; 76.9%) and repeated diarrhea (3 cases; 23.1%). Three (23.1%) of the patients had autoimmune disease and 10 (76.9%) had chronic pulmonary disease. IgG, IgA and IgM were decreased in all the patients. The proportion of CD4+T cells decreased in 10 patients (76.9%), CD8+T cells increased in 11 patients (84.6%), and CD4/ CD8 decreased in 10 patients (76.9%). Complement C3 decreased in 58.3% (7/12) and C4 decreased in 33.3% (4/12) of the patients. Twelve patients (92.3%) were treated with intravenous infusion of gamma globulin with symptomatic treatments. One patient died due to massive gastrointestinal hemorrhage, and the other patients showed improve ments after the treatments and were discharged.

CONCLUSIONS

The clinical manifestations of CVID are diverse, and recurrent respiratory tract infection is the most common manifestation. Decreased IgG often accompanied by lowered IgA and IgM levels is a common finding in laboratory tests. The treatment of CVID currently relies on gamma globulin with symptomatic treatments for the complications.

Phenotypic and Functional Analysis of T Follicular Cells in Common Variable Immunodeficiency

INTRODUCTION

One of the most frequent abnormalities of B cells in common variable immunodeficiency (CVID) is reduced number of class-switched memory B cells, suggesting an impaired germinal center response. Therefore, due to its pivotal role in regulating the development of humoral immunity, the objective of this study was to evaluate the role of circulating T follicular helper (cTFH) and circulating T follicular regulatory (cTFR) cells in the pathogenesis of CVID.

METHODS

cTFH and cTFR cells from CVID patients and healthy subjects were phenotypically characterized by flow cytometry. cTFH and memory B cells from CVID patients and healthy subjects were isolated and cocultured.

RESULTS

Our results showed a reduced proportion of cTFH17 cells in patients with CVID and an increased ratio of cTFH/cTFR cells in CVID patients with autoimmune diseases. Furthermore, the proportion of IL-21-producing cTFH cells was directly related to the proportion of CD27+ IgD- B cells. Interestingly, coculture assay showed that CVID-derived cTFH cells are able to help memory B cells from healthy controls to produce immunoglobulins.

CONCLUSIONS

The proportions of cTFH17 and cTFR cells are altered in CVID patients; however, the cTFH function in assisting B cells to produce antibodies in vitro is preserved.

Common Variable Immunodeficiency and Liver Involvement

Common variable immunodeficiency (CVID) is a primary B-cell immunodeficiency disorder, characterized by remarkable hypogammaglobulinemia. The disease can develop at any age without gender predominance. The prevalence of CVID varies widely worldwide. The underlying causes of CVID remain largely unknown; primary B-cell dysfunctions, defects in T cells and antigen-presenting cells are involved. Although some monogenetic defects have been identified in some CVID patients, it is likely that CVID is polygenic. Patients with CVID develop recurrent and chronic infections (e.g., bacterial infections of the respiratory or gastrointestinal tract), autoimmune diseases, lymphoproliferation, malignancies, and granulomatous lesions. Interestingly, autoimmunity can be the only clinical manifestation of CVID at the time of diagnosis and may even develop prior to hypogammaglobulinemia. The diagnosis of CVID is largely based on the criteria established by European Society for Immunodeficiencies and Pan-American Group for Immunodeficiency (ESID/PAGID) and with some recent modifications. The disease can affect multiple organs, including the liver. Clinical features of CVID patients with liver involvement include abnormal liver biochemistries, primarily elevation of alkaline phosphatase (ALP), nodular regenerative hyperplasia (NRH), or liver cirrhosis and its complications. Replacement therapy with immunoglobulin (Ig) and anti-infection therapy are the primary treatment regimen for CVID patients. No specific therapy for liver involvement of CVID is currently available, and liver transplantation is an option only in select cases. The prognosis of CVID varies widely. Further understanding in the etiology and pathophysiology will facilitate early diagnosis and treatments to improve prognosis.

Increase of follicular helper T cells skewed toward a Th1 profile in CVID patients with non-infectious clinical complications

Common variable immunodeficiency (CVID) is characterized by low levels of circulating immunoglobulins and defects in B cell maturation leading to an increased susceptibility to infections. Some patients develop complications such as autoimmune diseases, enteropathy, and lymphoproliferation, resulting in higher morbidity and mortality. Follicular helper T (Tfh) cells are specialized in helping B cell differentiation into Ig-producing cells. Three subsets have been described, namely non B-cell helper Tfh1 and the two B-helper cell subsets Tfh2 and Tfh17. We determined that circulating Tfh cells were elevated in CVID patients and skewed toward a Tfh1 profile. Interestingly, elevated levels of Tfh1 cells were significant only in patients harboring non-infectious complications regardless of the type of complication and inversely correlated with switched memory B cells. Moreover, CXCR3⁺ cells are increased in splenic CVID germinal centers. Our observations suggest that the altered balance in Tfh subsets in CVID is linked to a more severe disease.

Flow Cytometric Evaluation of Primary Immunodeficiencies

Primary immunodeficiency diseases are genetic disorders that mostly cause susceptibility to infections and are sometimes associated with autoimmune and malignant diseases. For early detection and management of these diseases, flow cytometric procedures allow an encompassing assessment of cellular phenotypes and cellular functions. State-of-the art cytometry is based today on 8- to 10-color staining and includes an assessment of lineage maturation and functional markers.