Hypogammaglobulinaemia during rituximab treatment in multiple sclerosis: A Swedish cohort study.

BACKGROUND AND PURPOSE: Mechanisms behind hypogammaglobulinaemia during rituximab treatment are poorly understood. METHODS: In this register-based multi-centre retrospective cohort study of multiple sclerosis (MS) patients in Sweden, 2745 patients from six participating Swedish MS centres were identified via the Swedish MS registry and included between 14 March 2008 and 25 January 2021. The exposure was treatment with at least one dose of rituximab for MS or clinically isolated syndrome, including data on treatment duration and doses. The degree of yearly decrease in immunoglobulin G (IgG) and immunoglobulin M (IgM) levels was evaluated. RESULTS: The mean decrease in IgG was 0.27 (95% confidence interval 0.17-0.36) g/L per year on rituximab treatment, slightly less in older patients, and without significant difference between sexes. IgG or IgM below the lower limit of normal (<6.7 or <0.27 g/L) was observed in 8.8% and 8.3% of patients, respectively, as nadir measurements. Six out of 2745 patients (0.2%) developed severe hypogammaglobulinaemia (IgG below 4.0 g/L) during the study period. Time on rituximab and accumulated dose were the main predictors for IgG decrease. Previous treatment with fingolimod and natalizumab, but not teriflunomide, dimethyl fumarate, interferons or glatiramer acetate, were significantly associated with lower baseline IgG levels by 0.80-1.03 g/L, compared with treatment-naïve patients. Switching from dimethyl fumarate or interferons was associated with an additional IgG decline of 0.14-0.19 g/L per year, compared to untreated. CONCLUSIONS: Accumulated dose and time on rituximab treatment are associated with a modest but significant decline in immunoglobulin levels. Previous MS therapies may influence additional IgG decline.

Association between hypogammaglobulinaemia and severe infections during induction therapy in ANCA-associated vasculitis: from J-CANVAS study.

OBJECTIVES: To investigate the association between decreased serum IgG levels caused by remission-induction immunosuppressive therapy of antineutrophil cytoplasmic antibody-associated vasculitis (AAV) and the development of severe infections. METHODS: We conducted a retrospective cohort study of patients with new-onset or severe relapsing AAV enrolled in the J-CANVAS registry, which was established at 24 referral sites in Japan. The minimum serum IgG levels up to 24 weeks and the incidence of severe infection up to 48 weeks after treatment initiation were evaluated. After multiple imputations for all explanatory variables, we performed the multivariate analysis using a Fine-Gray model to assess the association between low IgG (the minimum IgG levels <500 mg/dl) and severe infections. In addition, the association was expressed as a restricted cubic spline (RCS) and analysed by treatment subgroups. RESULTS: Of 657 included patients (microscopic polyangiitis, 392; granulomatosis with polyangiitis, 139; eosinophilic granulomatosis with polyangiitis, 126), 111 (16.9%) developed severe infections. The minimum serum IgG levels were measured in 510 patients, of whom 77 (15.1%) had low IgG. After multiple imputations, the confounder-adjusted hazard ratio of low IgG for the incidence of severe infections was 1.75 (95% confidence interval: 1.03-3.00). The RCS revealed a U-shaped association between serum IgG levels and the incidence of severe infection with serum IgG 946 mg/dl as the lowest point. Subgroup analysis showed no obvious heterogeneity between treatment regimens. CONCLUSION: Regardless of treatment regimens, low IgG after remission-induction treatment was associated with the development of severe infections up to 48 weeks after treatment initiation.

Associations between Antiepileptic Use and Hypogammaglobulinaemia: Findings from a Population-Based Case-Control Study Using Data Linkage.

BACKGROUND AND OBJECTIVES: Increased mortality in epilepsy due to infections (other than pneumonia) has been demonstrated. Small case series of people on antiepileptic drugs (AEDs) have described hypogammaglobulinaemia, which may predispose to infections. It is unclear whether hypogammaglobulinaemia is more frequent in people on AEDs, what AEDs it is associated with, or what clinical impact it has. In this population-based study, we aimed to determine whether AEDs were associated with hypogammaglobulinaemia, which AEDs were associated, and whether the associations may be causal. METHODS: We conducted an unmatched case-control study using data linkage of routinely collected biochemistry, prescribing, and morbidity datasets in North-East Scotland from 2009-2021. Cases were participants with immunoglobulin levels less than the reference range. Controls were those with normal/high immunoglobulin levels. Logistic regression was used to investigate associations between AED exposure and any hypogammaglobulinaemia, adjusting for age, sex, and comorbidity. We also analysed low IgA, IgM, and IgG separately. We analysed "any AED" exposure and common individual drugs separately. Cumulative exposure data were used to determine whether an exposure-response relationship was present. RESULTS: 18,666 cases and 127,157 controls were identified. Use of any AED was associated with increased risk of hypogammaglobulinaemia (adjusted odds ratio [aOR] 1.20 [95% CI: 1.15-1.25]). Phenytoin use was strongly associated with low IgA (aOR 5.90 [95% CI: 3.04, 10.43]). Carbamazepine and lamotrigine were also associated with low IgA. Apart from topiramate, which was associated with a non-significant decrease in odds of hypogammaglobulinaemia, there was a consistent increase in odds of hypogammaglobulinaemia across most AEDs studied. Panhypogammaglobulinaemia was associated with any AED use, carbamazepine, lamotrigine, gabapentin, and multiple AED use. There was evidence of an exposure-response relationship between any AED use and any hypogammaglobulinaemia, low IgA, and low IgG. Carbamazepine and probably lamotrigine also had an exposure-response relationship with any hypogammaglobulinaemia. DISCUSSION: AEDs may increase hypogammaglobulinaemia risk. Specific classes of immunoglobulins are differentially affected, and the exposure-response analysis suggests this may be causal. Further work should investigate the clinical impact of these findings. Clinicians should check immunoglobulin levels if unusual or recurrent infections occur in patients treated with AEDs.

New-onset hypogammaglobulinaemia and infectious complications associated with rituximab use in childhood-onset rheumatic diseases.

OBJECTIVE: To investigate the incidence and risk factors for hypogammaglobulinaemia and infectious complications associated with rituximab treatment in childhood-onset rheumatic diseases. METHODS: We performed a single-centre retrospective study of patients (n = 85) treated at Boston Children's Hospital (BCH) from 2009 to 2019. Study subjects included patients (ages 6-24 years) who received rituximab for the treatment of a childhood-onset rheumatic disease. RESULTS: New-onset hypogammaglobulinaemia developed in 23 (27.1%) patients within 18 months of rituximab induction treatment. Twenty-two patients (25.9%) developed at least one infectious complication in the 18 months following the first rituximab infusion; of these, 11 (50%) had serious infections requiring inpatient treatment. After adjusting for potential confounders, exposure to pulse corticosteroid therapy in the month prior to rituximab use was a significant predictor of both new-onset hypogammaglobulinaemia (odds ratio [OR] 3.94; 95% CI: 1.07, 16.0; P = 0.044) and infectious complications (OR 15.3; 95% CI: 3.04, 126.8; P = 0.003). Post-rituximab hypogammaglobulinaemia was the strongest predictor of serious infectious complications (OR 7.89; 95% CI: 1.41, 65.6; P = 0.028). Younger age at rituximab use was also a significant predictor of new-onset hypogammaglobulinaemia (OR 0.83; 95% CI: 0.70, 0.97; P = 0.021). Compared with other rheumatic diseases, patients with vasculitis had a higher likelihood of developing infectious complications, including serious infections. CONCLUSION: Although rituximab was well tolerated in terms of infectious complications in the majority of patients with childhood-onset rheumatic diseases, a substantial proportion developed new-onset hypogammaglobulinaemia and infectious complications following treatment. Our study highlights a role for heightened vigilance of rituximab-associated hypogammaglobulinaemia and infections in paediatric patients with rheumatic conditions.

Rituximab dose-dependent infection risk in rheumatoid arthritis is not mediated through circulating immunoglobulins, neutrophils or B cells.

OBJECTIVES: Rituximab (RTX) is a safe and effective treatment for RA. A dose-dependent infection risk was found in the REDO trial. Some studies associate RTX use with higher infection risks, possibly explained by low immunoglobulin levels and/or neutropenia. Additionally, a higher infection risk shortly after RTX infusion is reported. The objectives of this study were (i) to compare incidence rates of infections between doses and over time, and (ii) to assess B-cell counts, immunoglobulin levels, neutrophil counts and corticosteroid/disease modifying rheumatic drug use as mediating factors between RTX study dose and infection risk. METHODS: Post hoc analyses of the REDO trial were performed. Infection incidence rates between RTX dosing groups and between time periods were compared using Poisson regression. A step-wise mediation analysis was performed to investigate if any of the factors mentioned above act as a mediator in the observed dose-dependent difference in infection risk. RESULTS: The potential mediators that were investigated (circulating B-cell counts, immunoglobulin levels, neutrophil counts and drug use) did not explain the dose-dependent infection risk observed in the REDO trial. Additionally, a trend towards a time-dependent infection risk was found, with higher infection rates shortly after RTX infusion. CONCLUSIONS: These secondary analyses of the REDO trial confirmed the observed dose-dependent infection risk. Additionally, we found that infection risks were higher shortly after RTX infusion. However, a mediating pathway was not found.

Immunoglobulin replacement therapy in chronic lymphocytic leukaemia patients with hypogammaglobulinaemia and infection.

OBJECTIVES: To analyse total national utilisation of immunoglobulin (Ig) replacement therapy (IgRT) for Chronic Lymphocytic Leukaemia patients with acquired hypogammaglobulinaemia and severe and/or recurrent bacterial infections. METHODS: In 2007, the National Blood Authority first published Criteria for the clinical use of intravenous immunoglobulin in Australia. The Australian Red Cross Lifeblood assessed, approved, and recorded all supply with patient demographics, distribution data, intravenous Ig (IVIg) volumes and treatment episodes. IVIg was the sole product used in Australia from 2008-2013 inclusive. RESULTS: From 2008 to 2013 across Australia, 2734 individual CLL patients received 48,870 treatment episodes using a total 1,324,926 g of IVIg therapy. Six IVIg products were available, with domestically manufactured Intragam® P accounting for 89.7% of supply. The average age for first dose was 74 years. Males received 60.6% of the total treatment episodes representing 20% more than females. The average pre-treatment IgG level was 4.03 ± 2.03 g/L (range 0.30-10.50 g/L). A sustained average annual increased IVIg utilisation of 5.5% was observed. There was significant regional variation consistent with differences in prescriber preferences across states and territories. CONCLUSION: This study provides a globally unique insight into IgRT supply and demand in CLL patients by analysis of total national use in Australia over a 6-year period.

Antiviral treatment with fluoxetine for rituximab-associated chronic echovirus 13 meningoencephalitis and myofasciitis.

BACKGROUND AND PURPOSE: Enterovirus infections pose a serious threat for patients with humoral deficiencies and may be lethal, whilst the efficacy of proposed treatment options such as corticosteroids, intravenous immunoglobulins and fluoxetine remains debated. METHODS: Viral clearance was investigated in a patient with rituximab-induced B-cell depletion and chronic echovirus 13 (E13) meningoencephalitis/myofasciitis in response to intravenous immunoglobulins and fluoxetine using sequential semi-quantitative E13 viral load measurements by real-time reverse transcription polymerase chain reaction. Fluoxetine concentrations in plasma and cerebrospinal fluid were determined by liquid chromatography mass spectrometry. RESULTS: Intravenous immunoglobulins appeared ineffective in this case of E13 infection, whereas virus clearance in cerebrospinal fluid was obtained after 167 days of oral fluoxetine. Since treatment with corticosteroids resulted in a flare of symptoms, rechallenge with viral load measurements was not attempted. CONCLUSION: In this report of a patient with rituximab-associated chronic echovirus 13 meningoencephalitis, viral clearance in response to single treatment options is assessed for the first time. Our observations further support the in vivo efficacy of fluoxetine against enteroviral infections. More research is needed to establish its efficacy in different enterovirus strains.

Utility of immunology, microbiology, and helminth investigations in clinical assessment of severe asthma.

OBJECTIVE: Systematic assessment of patients with potential severe asthma is key to identification of treatable traits and optimal management. Assessment of antimicrobial immune function is part of that assessment at many centers although there is little evidence-base on its added value in clinical assessment of this patient group. As part of reviewing our local pathway, we have retrospectively reviewed these tests in 327 consecutive referrals to our severe asthma service, in an evaluation to describe the utility of these tests and allow refinement of the local guideline for patient assessment. METHODS AND RESULTS: Serum immunoglobulin concentrations were in the normal range in most patients though 12 patients had serum IgG < 5.5 g/L and many had suboptimal anti-Haemophilus (127 of 249 patients tested) and anti-Pneumococcal (111 of 239) immune responses. As expected many patients had evidence of sensitization to Aspergillus although specific IgG was not confined to those with evidence of allergic sensitization/allergic bronchopulmonary aspergillosis (ABPA). Eighteen of 277 patients tested had serological evidence of Strongyloides infection. Bacteria and/or yeast were cultured from the sputum in 76 out of 110 patients productive of sputum, and the most common microbes cultured were Candida sp. (44 patients), Staphylococcus aureus (21 patients), Haemophilus influenzae (18 patients). CONCLUSIONS: Many patients had evidence of infection, colonization, or sensitization to potential pathogens relevant to asthma. Strongyloides infection was evident in several patients, which may be a major issue when considering the risk of hyper-infection following immunosuppression and supports our local screening strategy.

Bronchiectasis is associated with delayed diagnosis and adverse outcomes in the New Zealand Common Variable Immunodeficiency Disorders cohort study.

Common variable immunodeficiency disorders (CVID) are multi-system disorders where target organ damage is mediated by infective, autoimmune and inflammatory processes. Bronchiectasis is probably the most common disabling complication of CVID. The risk factors for bronchiectasis in CVID patients are incompletely understood. The New Zealand CVID study (NZCS) is a nationwide longitudinal observational study of adults, which commenced in 2006. In this analysis, the prevalence and risk factors for bronchiectasis were examined in the NZCS. After informed consent, clinical and demographic data were obtained with an interviewer-assisted questionnaire. Linked electronic clinical records and laboratory results were also reviewed. Statistical methods were applied to determine if variables such as early-onset disease, delay in diagnosis and increased numbers of infections were associated with greater risk of bronchiectasis. One hundred and seven adult patients with a diagnosis of CVID are currently enrolled in the NZCS, comprising approximately 70% of patients known to have CVID in New Zealand. Fifty patients (46·7%) had radiologically proven bronchiectasis. This study has shown that patients with compared to those without bronchiectasis have an increased mortality at a younger age. CVID patients with bronchiectasis had a greater number of severe infections consequent to early-onset disease and delayed diagnosis. Indigenous Maori have a high prevalence of CVID and a much greater burden of bronchiectasis compared to New Zealand Europeans. Diagnostic latency has not improved during the study period. Exposure to large numbers of infections because of early-onset disease and delayed diagnosis was associated with an increased risk of bronchiectasis. Earlier diagnosis and treatment of CVID may reduce the risk of bronchiectasis and premature death in some patients.

Case report of Ureaplasma urealyticum meningitis in a patient with thymoma and hypogammaglobulinaemia.

BACKGROUND: Ureaplasma urealyticum (UU) is found among the normal vaginal flora in a considerable proportion of asymptomatic women; however, adult central nervous system (CNS) infection of UU is extremely rare. Good's syndrome (GS) is an adult-onset immunodeficiency characterized by thymoma, hypogammaglobulinaemia, low or absent B­cells, and an inverted CD4+/CD8+ T­cell ratio. Patients with GS usually have severe or recurrent infections. CASE PRESENTATION: We describe the case report of a 49-year-old woman who developed UU meningitis. Initial routine anti-viral and anti-bacterial therapy showed no improvement in the patient's condition. Next-generation sequencing (NGS) of cerebrospinal fluid (CSF) identified the UU DNA sequence. Accordingly, a diagnosis of UU meningitis was made, and minocycline therapy was initiated. The patient responded favourably, with no signs of disease at subsequent follow-up. According to the severity and rarity of the case, secondary immunodeficiency was suspected. Flow cytometry found hypogammaglobulinaemia. Combined with the previous history of thymoma, the patient was diagnosed with immune deficiency disease of GS. CONCLUSIONS: This case may be the first adult case report in the literature describing UU meningitis in a patient with GS. The diagnosis of GS should be considered in patients presenting with unexplained antibody deficiency and thymoma.

British Society for Immunology/United Kingdom Primary Immunodeficiency Network consensus statement on managing non-infectious complications of common variable immunodeficiency disorders.

Common variable immunodeficiency (CVID) represents a heterogeneous group of rare disorders. There is considerable morbidity and mortality as a result of non-infectious complications, and this presents clinicians with management challenges. Clinical guidelines to support the management of CVID are urgently required. The UK Primary Immunodeficiency Network and the British Society for Immunology funded a joint project to address this. A modified Delphi Survey was conducted for the assessment, diagnosis and treatment of the non-infectious blood, respiratory, gut and liver complications of CVID. A steering group of 10 consultant immunologists and one nurse specialist developed and reviewed the survey statements and agreed the final recommendations. In total, 22 recommendations and three areas for research were developed.

Transient hypogammaglobulinaemia of infancy: many patients recover in adolescence and adulthood.

Transient hypogammaglobulinaemia of infancy (THI) is a relatively rare disorder where there is an exaggeration of the physiological nadir of immunoglobulin (Ig)G between loss of transplacentally acquired maternal IgG and production by the infant. Patients may be vulnerable to infections during the period of hypogammaglobulinaemia. The precise time to recovery in all infants is currently unknown. We sought to determine the clinical features and time-course of recovery for patients with THI. We reviewed our experience with THI over the last three decades in order to describe clinical and laboratory features, as well as the time-course of recovery. Forty-seven patients were identified with THI. Only thirty-seven per cent remitted by 4 years of age, while some patients did not recover until the third or fourth decade. In keeping with previous studies, the majority (25 of 47) presented with recurrent infections, nine had a family history of immunodeficiency and 13 had adverse reactions to food as their dominant clinical manifestation. Chronic tonsillitis developed in 10 patients and symptoms improved following surgery. The group with food allergies recovered sooner than those presenting with infections or with a family history immunodeficiency. Eight patients failed to respond to at least one routine childhood vaccine. Two have IgA deficiency and four individuals recovering in adolescence and adulthood continue to have borderline/low IgG levels. None have progressed to common variable immunodeficiency disorders (CVID). THI is a misnomer, as the majority do not recover in infancy. Recovery from THI can extend into adulthood. THI must be considered in the differential diagnosis of adolescents or young adults presenting with primary hypogammaglobulinemia.

Managing hypogammaglobulinaemia secondary to haematological malignancies in Australia and New Zealand: a clinician survey.

BACKGROUND: Acquired hypogammaglobulinaemia secondary to haematological malignancies is associated with increased infection risk. Immunoglobulin (Ig) replacement reduces major infections but not mortality, and is costly. No prospective randomised trials have compared Ig replacement with prophylactic antibiotics. AIMS: To identify variation in current practice regarding management of secondary hypogammaglobulinaemia in Australia and New Zealand, to identify barriers to best practice, and to inform the development of a clinical trial assessing antibiotic prophylaxis in secondary hypogammaglobulinaemia. METHODS: We conducted an online survey of current clinical practice regarding management of secondary hypogammaglobulinaemia among haematologists in Australia and New Zealand. RESULTS: Seventy-two haematologists responded; 89% of whom reported commencing Ig replacement for secondary hypogammaglobulinaemia in the setting of recurrent or severe infection. Most monitored trough immunoglobulin G levels, most often 3 monthly. Criteria for stopping Ig replacement varied. Most respondents recommended influenza and pneumococcal vaccination, while only 21% reported using antibiotic prophylaxis. Few respondents (3%) reported prescribing prophylactic antibiotics before commencing Ig replacement. Most reported an interest in recruiting patients to a clinical trial comparing Ig replacement with prophylactic antibiotics. CONCLUSION: In comparison to limited international data, this survey finds variation in practice, which may be due to differences in local policies governing access to Ig. These findings highlight the need for research into the indications for Ig commencement and cessation, and will inform design of prospective trials of infection prevention in secondary hypogammaglobulinaemia.

Immunoglobulinopathies in patients with angioimmunoblastic T-cell lymphoma.

AIM: The aim of the study was to characterize quantitative and qualitative immunoglobulinopathies in patients with AITL at the onset of the disease. MATERIALS AND METHODS: 55 patients with newly diagnosed AITL were enrolled in the study, the male/female ratio was 30/25; median age was 61 (29-81) years. Diagnosis was based on standard WHO criteria. Immunochemical studies of blood serum included serum protein electrophoresis/immunofixation, nephelometric quantification of total immunoglobulins, serum free light chain assay. RESULTS: Quantitative and qualitative immunoglobulinopathies were determined in 49 (89,1%) of 55 pts. Quantitative immunoglobulinopathies were revealed in 47 (85.5%) of 55 cases, qualitative - in 14 (25,5%). Combination quantitative and qualitative immunoglobulinopathies was observed in 12 (21,8%) of 55 pts. The detected immunoglobulinopathies were divided into 4 groups: polyclonal hypergammaglobulinaemia, hypogammaglobulinaemia, oligoclonal gammapathy, and monoclonal gammapathy. Polyclonal hypergammaglobulinaemia was marked in 41 (74.5%) of 55 pts, elevated level of IgG was determined in 27 (49,15%) of 55 cases, IgM - in 18 (32,7%) and IgA - in 21 (38.2%). Interestingly, polyclonal IgE hypergammaglobulinaemia was detected in 12 (48,0%) of 25 cases of performed studies. Hypogammaglobulinaemia was detected in 8 (14,5%) of 55 cases. Oligoclonal gammapathy was determined in 4 (7.3%) of 55 pts. Monoclonal gammapathy was revealed in 11 (20,0%) of 55 cases. The amount of monoclonal immunoglobulin varied from 2.6 to 14.1 g/l. Monoclonal immunoglobulin Gk was detected in 5 of 11 pts, Gλ - in 2, Mλ - in 2, Mk - in 2. Monoclonal gammapathy was accompanied by polyclonal hypergammaglobulinaemia in 9 of 11 cases, hypogammaglobulinaemia - in 2. CONCLUSION: Quantitative and qualitative immunoglobulinopathies are observed in most patients at the onset of AITL. Quantitative abnormalities were determined more often than qualitative. Monoclonal gammapathy can be a manifestation of lymphoproliferation and other concomitant disorders. The prognostic value of immunochemical parameters is still unclear and requires dynamic observation and study.

Bronchiectasis following treatment for high-risk neuroblastoma: A case series.

High-risk (HR) neuroblastoma remains a very challenging disease to treat and long-term cure is only possible with intensive, multimodal treatment including chemotherapy, high-dose therapy, radiotherapy, surgery, and immunotherapy. As a result, treatment-related morbidity and late effects are common in survivors. This report outlines a case series of six patients who developed a chronic productive cough following treatment for HR neuroblastoma. High-resolution computed tomography scanning confirmed the diagnosis of bronchiectasis. Two of the patients who have undergone immunological testing demonstrate hypogammaglobulinaemia and impaired vaccine response. Persistent cough in patients treated for neuroblastoma warrants investigation and consideration of immunological referral.

Ureaplasma urealyticum necrotizing soft tissue infection.

Ureaplasma urealyticum is a urogenital commensal and often associated with localised infection. With the advent of monoclonal immunosuppressive therapy and improved diagnostic methods, reports of non-urogenital infections are accumulating. We report a rare case of U. urealyticum necrotizing soft tissue infection and left hip septic arthritis in a hypogammaglobulinaemic patient. Consideration of this organism as an etiological agent, and potential early use of nucleic-acid diagnostic investigation with empiric therapy including activity against Ureaplasma in this patient population may be warranted.

Primary immunodeficiency diseases in Northern Iran.

INTRODUCTION: Primary immunodeficiency diseases (PID) are a heterogeneous group of inherited disorders, characterised by recurrent severe infections, autoimmunity and lymphoproliferation. Despite impressive progress in identification of novel PID, there is an unfortunate lack of awareness among physicians in identification of patients with PID, especially in non-capital cities of countries worldwide. RESULT: This study was performed in a single-centre paediatric hospital in Northern Iran during a 21-year period (1994-2015). Ninety-four patients were included in this study. The majority of cases had antibody deficiencies (37.23%), followed by well-defined syndromes with immunodeficiency in 16 (17.02%), phagocytic disorders in 15 patients (15.95%), complement deficiencies in 15 patients (15.95%), immunodeficiencies affecting cellular and humoral immunity in nine patients (9.57%), disease of immune dysregulation in three (3.19%), and defects in intrinsic and innate immunity in one (1.06%). CONCLUSION: It seems that there are major variations in frequency of different types of PID in different regions of a country. Therefore, reporting local data could provide better ideas to improve the local health care system strategists and quality of care of PID patients.

Activating PI3Kδ mutations in a cohort of 669 patients with primary immunodeficiency.

The gene PIK3CD codes for the catalytic subunit of phosphoinositide 3-kinase δ (PI3Kδ), and is expressed solely in leucocytes. Activating mutations of PIK3CD have been described to cause an autosomal dominant immunodeficiency that shares clinical features with common variable immunodeficiency (CVID). We screened a cohort of 669 molecularly undefined primary immunodeficiency patients for five reported mutations (four gain-of-function mutations in PIK3CD and a loss of function mutation in PIK3R1) using pyrosequencing. PIK3CD mutations were identified in three siblings diagnosed with CVID and two sporadic cases with a combined immunodeficiency (CID). The PIK3R1 mutation was not identified in the cohort. Our patients with activated PI3Kδ syndrome (APDS) showed a range of clinical and immunological findings, even within a single family, but shared a reduction in naive T cells. PIK3CD gain of function mutations are more likely to occur in patients with defective B and T cell responses and should be screened for in CVID and CID, but are less likely in patients with a pure B cell/hypogammaglobulinaemia phenotype.

A comparison of B cell subsets in primary immune deficiencies that progress with antibody deficiency and age-matched healthy children.

BACKGROUND: The objective of this study was to examine the B lymphocyte subsets in primary immunodeficiency that progress with antibody deficiency. METHODS: The patients' naive, memory, class-switched memory and non-switched memory B cells were compared with those of healthy individuals of matching ages using flow cytometry. RESULTS: A total of 67 patients with antibody deficiency and 28 healthy children of matching ages were included in the study. The median age of the patients was six years (min-max: 1-24) and 40 (59.7%) were male. The median age of the healthy controls was again six years (min-max: 1-17) and 12 (42.8%) were male. Patients with common variable immunodeficiency had higher relative counts of naive cells when compared with the control group; however, they were found to have lower relative counts of memory, relative and absolute counts of non-switched and relative counts of switched B lymphocytes (p=0.001, 0.023, 0.003-0.003, 0.001, respectively). In patients with selective IgA deficiency, similar to patients with common variable immunodeficiency, the relative counts of naive cells were found to be higher, while the relative counts of memory and relative and absolute counts of non-switched B lymphocytes were found to be lower when compared with the control group (p=0.011, 0.032, 0.006-0.009, respectively). Although patients with selective IgM deficiency had higher relative counts of naive B cells when compared with the control group, they had lower relative and absolute counts of non-switched B lymphocytes (p=0.008-0.016). CONCLUSIONS: The B lymphocyte subsets of patients with selective IgA deficiency are largely similar to those of patients with common variable immunodeficiency. Both illness groups exhibit low levels of memory B cells.