Stephan Borte

Clinical picture and treatment of 2212 patients with common variable immunodeficiency

BACKGROUND Common variable immunodeficiency (CVID) is an antibody deficiency with an equal sex distribution and a high variability in clinical presentation. The main features include respiratory tract infections and their associated complications, enteropathy, autoimmunity, and lymphoproliferative disorders. OBJECTIVE This study analyzes the clinical presentation, association between clinical features, and differences and effects of immunoglobulin treatment in Europe. METHODS Data on 2212 patients with CVID from 28 medical centers contributing to the European Society for Immunodeficiencies Database were analyzed retrospectively. RESULTS Early disease onset (<10 years) was very frequent in our cohort (33.7%), especially in male subjects (39.8%). Male subjects with early-onset CVID were more prone to pneumonia and less prone to other complications suggesting a distinct disease entity. The diagnostic delay of CVID ranges between 4 and 5 years in many countries and is particularly high in subjects with early-onset CVID. Enteropathy, autoimmunity, granulomas, and splenomegaly formed a set of interrelated features, whereas bronchiectasis was not associated with any other clinical feature. Patient survival in this cohort was associated with age at onset and age at diagnosis only. There were different treatment strategies in Europe, with considerable differences in immunoglobulin dosing, ranging from 130 up to 750 mg/kg/mo. Patients with very low trough levels of less than 4 g/L had poor clinical outcomes, whereas higher trough levels were associated with a reduced frequency of serious bacterial infections. CONCLUSION Patients with CVID are being managed differently throughout Europe, affecting various outcome measures. Clinically, CVID is a truly variable antibody deficiency syndrome.

Neonatal screening for severe primary immunodeficiency diseases using high-throughput triplex real-time PCR

Severe combined immunodeficiency (SCID) and X-linked agammaglobulinemia (XLA) are inborn errors of immune function that require prompt diagnosis and treatment to prevent life-threatening infections. The lack of functional T or B lymphocytes in these diseases serves as a diagnostic criterion and can be applied to neonatal screening. A robust triplex PCR method for quantitation of T-cell receptor excision circles (TRECs) and κ-deleting recombination excision circles (KRECs), using a single Guthrie card punch, was developed and validated in a cohort of 2560 anonymized newborn screening cards and in 49 original stored Guthrie cards from patients diagnosed with SCID, XLA, ataxia-telangiectasia, Nijmegen-breakage-syndrome, common variable immunodeficiency, immunoglobulin A deficiency, or X-linked hyper-IgM syndrome. Simultaneous measurement of TREC and KREC copy numbers in Guthrie card samples readily identified patients with SCID, XLA, ataxia-telangiectasia and Nijmegen-breakage-syndrome and thus facilitates effective newborn screening for severe immunodeficiency syndromes characterized by the absence of T or B cells.

Combined immunodeficiency and Epstein-Barr virus?induced B cell malignancy in humans with inherited CD70 deficiency

In this study, we describe four patients from two unrelated families of different ethnicities with a primary immunodeficiency, predominantly manifesting as susceptibility to Epstein-Barr virus (EBV)–related diseases. Three patients presented with EBV-associated Hodgkin’s lymphoma and hypogammaglobulinemia; one also had severe varicella infection. The fourth had viral encephalitis during infancy. Homozygous frameshift or in-frame deletions in CD70 in these patients abolished either CD70 surface expression or binding to its cognate receptor CD27. Blood lymphocyte numbers were normal, but the proportions of memory B cells and EBV-specific effector memory CD8+ T cells were reduced. Furthermore, although T cell proliferation was normal, in vitro–generated EBV-specific cytotoxic T cell activity was reduced because of CD70 deficiency. This reflected impaired activation by, rather than effects during killing of, EBV-transformed B cells. Notably, expression of 2B4 and NKG2D, receptors implicated in controlling EBV infection, on memory CD8+ T cells from CD70-deficient individuals was reduced, consistent with their impaired killing of EBV-infected cells. Thus, autosomal recessive CD70 deficiency is a novel cause of combined immunodeficiency and EBV-associated diseases, reminiscent of inherited CD27 deficiency. Overall, human CD70–CD27 interactions therefore play a nonredundant role in T and B cell–mediated immunity, especially for protection against EBV and humoral immunity.

Newborn screening for primary immunodeficiencies: beyond SCID and XLA

Primary immunodeficiencies (PID) encompass more than 250 disease entities, including phagocytic disorders, complement deficiencies, T cell defects, and antibody deficiencies. While differing in clinical severity, early diagnosis and treatment is of considerable importance for all forms of PID to prevent organ damage and life‐threatening infections. During the past few years, neonatal screening assays have been developed to detect diseases hallmarked by the absence of T or B lymphocytes, classically seen in severe combined immunodeficiencies (SCID) and X‐linked agammaglobulinemia (XLA). As described in this review, a reduction or lack of T and B cells in newborns is also frequently found in several other forms of PID, requiring supplemental investigation and involving the development of additional technical platforms in order to help classify abnormal screening results.

Eight-color immunophenotyping of T-, B-, and NK-cell subpopulations for characterization of chronic immunodeficiencies

The heterogeneity of primary and secondary immunodeficiencies demands for the development of a comprehensive flow cytometric screening system, based on reference values that support a standardized immunophenotypic characterization of most lymphocyte subpopulations.

RAC2 loss-of-function mutation in 2 siblings with characteristics of common variable immunodeficiency

in IL-10 and IL-13 regulation in monocytes. Therefore we treated PBMCs from patients with AD who were sensitized to Mala s 13 with lactic acid to remove surface-bound IgE. By using this treatment, surface levels of IgE on monocytes were reduced (Fig 1,D), and IL-10 secretion was significantly increased after Mala s 13 stimulation but not after hTrx stimulation (Fig 1, E). In contrast, IL-13 secretion could be reduced after lactic acid treatment followed by hTrx stimulation but not by Mala s 13 stimulation (Fig 1, E). An explanation for these discrepancies might be the small fraction of Mala s 13– and hTrx-specific IgE in relation to the patient’s total serum IgE levels. In fact, the increase in IL-10 levels after IgE stripping and stimulation with Mala s 13 correlated with the Malassezia species–specific IgE/total IgE ratio (Spearman r 5 0.536, P 5 .048). In turn, this can be explained by the correlation of monocyte surface levels of FcεRI with total serum IgE levels. Our findings are in contrast to those of previous reports showing an increased IL-10 secretion of FcεRI-activated monocytes. This might be due to differences in the experimental setup, such as the use of monoclonal IgE and anti-IgE for receptor crosslinking compared with our assay by using 1 distinct allergen, as well as due to different cell-culture conditions and the time point of analysis. Using anti-IgE stimulation, we could also upregulate IL-10 in PMBCs from patients with AD who were sensitized to Malassezia species (see Fig E3 in this article’s Online Repository at www.jacionline.org). Therefore this discrepancy between massive IgE receptor cross-linking with anti-IgE and the potentially weaker cross-linking resulting from application of native allergens should be considered in future studies. The major findings of this study are (1) an IgE-dependent upregulation of the TH2 cytokine IL-13 by hTrx and (2) an impaired upregulation of IL-10 by hTrx in patients with AD who were sensitized to Mala s 13 and hTrx. IL-10 promotes the development of regulatory dendritic cells and T cells and therefore tolerance, and it is involved in a number of processes involved in the downregulation of a local inflammatory response. The relative lack of antigen-specific IL-10 secretion in PBMCs from patients with AD whowere sensitized toMalassezia species might contribute to the perpetuation of the local cutaneous inflammation in patients with AD and to further development of TH2and IgE-mediated immune responses. Moreover, specific sensitization against hTrx can directly be involved in disease exacerbation in patients with AD because hTrx can be released from dermal or epidermal cells and might then promote inflammatory responses by activating specific T cells and cells expressing receptors for IgE.

Prospective neonatal screening for severe T‐ and B‐lymphocyte deficiencies in Seville

Early diagnosis of primary immunodeficiency such as severe combined immunodeficiency (SCID) and X‐linked agammaglobulinemia (XLA) improves outcome of affected children. T‐cell‐receptor‐excision circles (TRECs) and kappa‐deleting‐recombination‐excision circles (KRECs) determination from dried blood spots (DBS) identify neonates with severe T‐ and/or B‐lymphopenia. No prospective data exist of the impact of gestational age (GA) and birth weight (BW) on TRECs and KRECs values.

Primer estudio piloto en España sobre el cribado neonatal de las inmunodeficiencias primarias: TRECS y KRECS identifican linfopenias T y B graves

INTRODUCTION Early diagnosis of primary immunodeficiency such as severe combined immunodeficiency (SCID) and X-linked agammaglobulinemia (XLA) improves outcome of affected infants/children. The measurement of T-cell receptor excision circles (TRECS) and kappa-deleting recombination excision circles (KRECS) can identify neonates with severe T or B-cell lymphopenia. OBJECTIVES To determine TRECS and KRECS levels from prospectively collected dried blood spot samples (DBS) and to correctly identify severe T and B-cell lymphopenia. MATERIAL AND METHODS Determination of TRECS and KRECS by multiplex PCR from neonates born in two tertiary hospitals in Seville between February 2014 and May 2014. PCR cut-off levels: TRECS<15 copies/μl, KRECS<10 copies/μl, ACTB (β-actin)>1000 copies/μl. Internal (XLA, ataxia telangiectasia) and external (SCID) controls were included. RESULTS A total of 1068 out of 1088 neonates (mean GA 39 weeks (38-40) and BW 3238g (2930-3520) were enrolled in the study. Mean (median, min/max) copies/μl, were as follows: TRECS 145 (132, 8/503), KRECS 82 (71, 7/381), and ACTB 2838 (2763, 284/7710). Twenty samples (1.87%) were insufficient. Resampling was needed in one neonate (0.09%), subsequently giving a normal result. When using lower cut-offs (TRECS<8 and KRECS<4 copies/μl), all the samples tested were normal and the internal and external controls were correctly identified. CONCLUSION This is the first prospective pilot study in Spain using TRECS/KRECS/ACTB-assay, describing the experience and applicability of this method to identify severe lymphopenias. The ideal cut-off remains to be established in our population. Quality of sampling, storage and preparation need to be further improved.

Placental Transfer of Maternally-Derived IgA Precludes the Use of Guthrie Card Eluates as a Screening Tool for Primary Immunodeficiency Diseases

There is a need for neonatal screening tools to improve the long-term clinical outcome of patients with primary immunodeficiency diseases (PID). Recently, a PCR-based screening method for both TRECs and KRECs using Guthrie card samples has been developed. However, the applicability of these excision circle assays is limited to patients with severe T or B cell lymphopenia (SCID, XLA and A-T), whereas the most common forms of PID are not detected. Absence of serum IgA is seen in a major fraction of patients with immunological defects. As serum IgA in newborns is considered to be of fetal origin, eluates from routinely collected dried blood spot samples might thus be suitable for identification of children with PID. To assess the applicability of such screening assays, stored Guthrie card samples were obtained from 47 patients with various forms of primary immunodeficiency diseases (SCID, XLA, A-T, HIGM and IgAD), 20 individuals with normal serum IgA levels born to IgA-deficient mothers and 51 matched healthy newborns. Surprisingly, normal serum IgA levels were found in all SCID, XLA, A-T and HIGM patients and, additionally, in all those IgAD patients born to IgA-sufficient mothers. Conversely, no serum IgA was found in any of the 16 IgAD patients born by IgA-deficient mothers. Moreover, half of the IgA-sufficient individuals born by IgA-deficient mothers also lacked IgA at birth whereas no IgA-deficient individuals were found among the controls. IgA in neonatal dried blood samples thus appears to be of both maternal and fetal origin and precludes its use as a reliable marker for neonatal screening of primary immunodeficiency diseases.

Novel NLRP12 mutations associated with intestinal amyloidosis in a patient diagnosed with common variable immunodeficiency.

Heterozygous mutations in the NLRP12 gene have been found in patients with systemic auto-inflammatory diseases. However, the NLRP12-associated periodic fever syndromes show a wide clinical spectrum, including patients without classical diagnostic symptoms. Here, we report on a 20-year-old female patient diagnosed with common variable immunodeficiency (CVID), who developed intestinal amyloidosis and carried novel compound heterozygous mutations in NLRP12, identified by whole exome and transcriptome sequencing. CVID is a primary immunodeficiency characterized by low serum immunoglobulins, recurrent bacterial infections and development of malignancy, but it also presents with a magnitude of autoimmune features. Because of the unspecific heterogeneous clinical features of the disease, a delay in diagnosis is common. Secondary, inflammatory (AA type) amyloidosis has infrequently been observed in CVID patients. Based on our case observation and a critical review of the literature, we suggest that NLRP12 mutations might account for a small fraction of CVID patients with severe auto-inflammatory complications.