The molecular pathology of primary immunodeficiencies

VIPPID: a gene-specific single nucleotide variant pathogenicity prediction tool for primary immunodeficiency diseases

Distinguishing pathogenic variants from non-pathogenic ones remains a major challenge in clinical genetic testing of primary immunodeficiency (PID) patients. Most of the existing mutation pathogenicity prediction tools treat all mutations as homogeneous entities, ignoring the differences in characteristics of different genes, and use the same model for genes in different diseases. In this study, we developed a single nucleotide variant (SNV) pathogenicity prediction tool, Variant Impact Predictor for PIDs (VIPPID; https://mylab.shinyapps.io/VIPPID/), which was tailored for PIDs genes and used a specific model for each of the most prevalent PID known genes. It employed a Conditional Inference Forest model and utilized information of 85 features of SNVs and scores from 20 existing prediction tools. Evaluation of VIPPID showed that it had superior performance (area under the curve = 0.91) over non-specific conventional tools. In addition, we also showed that the gene-specific model outperformed the non-gene-specific models. Our study demonstrated that disease-specific and gene-specific models can improve SNV pathogenicity prediction performance. This observation supports the notion that each feature of mutations in the model can be potentially used, in a new algorithm, to investigate the characteristics and function of the encoded proteins.

Approach to genetic diagnosis of inborn errors of immunity through next-generation sequencing

Patients with inborn errors of immunity (IEI) present with a heterogeneous clinical and immunological phenotype, therefore a correct molecular diagnosis is crucial for the classification and subsequent therapeutic management. On the other hand, IEI are a group of rare congenital diseases with highly diverse features and, in most cases, an as yet unknown genetic etiology. Next generation sequencing has facilitated genetic examinations of rare inherited disorders during the recent years, thus allowing a suitable molecular diagnosis in the IEI patients. This review aimed to investigate the current findings about these techniques in the field of IEI, suggesting an efficient stepwise approach to molecular diagnosis of inborn errors of immunity.

Targeting the MHC Class II antigen presentation pathway in cancer immunotherapy

The success of immunotherapy relies on the participation of all arms of the immune system and the role of CD4+ T lymphocytes in preventing tumor growth is now well established. Understanding how tumors evade immune responses holds the key to the development of cancer immunotherapies. In this review, we discuss how MHC Class II expression varies in cancer cells and how this influences antitumor immune responses. We also discuss the means that are currently available for harnessing the MHC Class II antigen presentation pathway for the development of efficient vaccines to activate the immune system against cancer.

Altered plasma levels of βC and γC chain cytokines and post-treatment modulation in tuberculous lymphadenitis

BACKGROUND

Alterations in β common (βC) and γ common (γC) chain cytokines have been described in pulmonary tuberculosis. However, their role in tuberculous lymphadenitis (TBL) disease has not been assessed.

METHODS

Thus, in the present study, we have examined the systemic levels of βC and γC chain cytokines in TBL, latent tuberculosis (LTB) and healthy control (HC) individuals. We have examined the discriminatory potential of both family of cytokines using ROC analysis. Finally, we measured the pre and post-treatment responses of these cytokines after anti-tuberculosis treatment.

RESULTS

TBL individuals exhibit significantly increased (IL-3) and diminished systemic levels of (IL-5, GM-CSF) βC cytokines compared to LTB and HC individuals. TBL individuals also exhibit significantly diminished (IL-2, IL-7) and elevated (IL-4, IL-9) levels of γC cytokines compared to LTB and/or HC. ROC analysis shows a clear discriminatory capacity of both βC (IL-5) and γC (IL-2) chain cytokines to distinguish TBL from LTB and HCs. The systemic levels of βC chain cytokines were not significantly altered, but in contrast γC (IL-2 and IL-7) cytokines were significantly modulated after treatment. Finally, no significant correlation was observed for βC and γC chain cytokines with their respective lymphocyte count of TBL individuals.

CONCLUSIONS

Hence, we conclude that altered plasma levels of βC and γC cytokines are the characteristics of immune alteration in TBL disease and certain cytokines were modulated after treatment.

The MHC-II antigen presentation machinery and B7 checkpoint ligands display distinctive patterns correlated with acute myeloid leukaemias blast cells HLA-DR expression

Acute Myeloid Leukaemia (AML) is a neoplasia characterised by rapid proliferation and an increased rate of relapses. The AML blasts display features of antigen-presenting cells (APC), and thus can directly modulate the anti-tumour T cell responses. The bone marrow of a group consisting of 30 newly diagnosed patients and four healthy donors (HD) was investigated for the expression of HLA-DR, several molecules involved in MHC-II antigen-presentation and MHC-II groove editing, like HLA-DM, CD74 and CLIP, as well as a set of immune checkpoint ligands, like ICOS-L, B7.2, PD-L2 and B7-H3. The patients were further characterised for their genetic anomalies and distributed to favourable, intermediate and adverse ELN risk categories. We were able to show that while 23% of our patients displayed a low level of HLA-DR surface expression, all patients displayed higher HLA-DM and CD74 expression compared to HD. However, a higher CLIP expression was noticed only in the HLA-DR low patients. The co-inhibitory PD-L2 and B7-H3 molecules were increased in the cases with normal HLA-DR expression; oppositely, the co-stimulatory ICOS-L and the dual function B7.2 were significantly increased in the cases with HLA-DR low expression. Furthermore, no favourable ELN risk cases were found within the HLA-DR low group. All in all, these data show that the AML with low versus normal HLA-DR expression display different profiles of MHC class II machinery molecules and B7 ligands, which are correlated with distinct ELN stratification. Furthermore, as our study included healthy individuals, it offers valuable information about the expression levels that should be considered as normal for these markers known to cause differences in peptide repertoires, reflected further in distinct T-cells polarisation pathways.

Correlations Among Subcutaneous Immunoglobulin Dosage, Immunoglobulin G Serum Pre-infusional Levels and Body Mass Index in Primary Antibody Deficiency Patients: A Pooled Analysis from the SHIFT/IBIS Studies

Background and Objective

In recent years, two Italian non-interventional studies evaluated subcutaneous immunoglobulin (SCIG) treatment in patients affected by primary antibody deficiency (PAD). The SHIFT study considered patients who were treated with intravenous immunoglobulin (IVIG) or SCIG 16% (Vivaglobin^®) and then replaced this therapy with weekly treatments of SCIG 20% (Hizentra^®). The IBIS study evaluated patients previously taking a weekly SCIG 20% regimen, who instead began therapy with biweekly SCIG 20% to assess the correlation between the dose of immunoglobulin G (IgG) administered and the body mass index (BMI) of patients, determine if there is a need for dosage adjustments on a BMI basis, and identify the predictors of serum IgG trough levels in our cohort.

Methods

In this study, we analyzed the pooled data of 109 PAD patients enrolled in the SHIFT and IBIS studies. Only prospective phases were considered.

Results

The total monthly SCIG dose showed comparable trends among weight categories, except for underweight patients. When we considered the monthly SCIG dosage per kilogram of body weight, a significant decreasing trend according to BMI was observed. Data on IgG trough levels were available for 88 patients, with a mean IgG serum level of 8.4 ± 1.6 g/L. A stepwise regression model revealed that the mean monthly dosage of SCIG 20% (p = 0.04248) and the mean monthly dosage of IgG per kilogram of body weight were the only two independent predictors associated with IgG trough levels. No association was found between BMI and IgG trough levels.

Conclusions

These findings support the concept that the cumulative monthly dose of SCIG and the dose of SCIG per kilogram of body weight affect IgG trough levels in PAD patients, irrespective of BMI.

Newborn Screening for Presymptomatic Diagnosis of Complement and Phagocyte Deficiencies

The clinical outcomes of primary immunodeficiencies (PIDs) are greatly improved by accurate diagnosis early in life. However, it is not common to consider PIDs before the manifestation of severe clinical symptoms. Including PIDs in the nation-wide newborn screening programs will potentially improve survival and provide better disease management and preventive care in PID patients. This calls for the detection of disease biomarkers in blood and the use of dried blood spot samples, which is a part of routine newborn screening programs worldwide. Here, we developed a newborn screening method based on multiplex protein profiling for parallel diagnosis of 22 innate immunodeficiencies affecting the complement system and respiratory burst function in phagocytosis. The proposed method uses a small fraction of eluted blood from dried blood spots and is applicable for population-scale performance. The diagnosis method is validated through a retrospective screening of immunodeficient patient samples. This diagnostic approach can pave the way for an earlier, more comprehensive and accurate diagnosis of complement and phagocytic disorders, which ultimately lead to a healthy and active life for the PID patients.

Inmunodeficiencia combinada severa (SCID) en Neiva, Colombia. Reporte de caso

Introducción. Las inmunodeficiencias primarias son enfermedades genéticas del sistema inmune que incrementan la susceptibilidad a infecciones. Una de las formas más graves en niños es la inmunodeficiencia combinada severa.Presentación del caso. Se presenta el caso de un niño que fue diagnosticado con inmunodeficiencia combinada severa; este era un paciente masculino de ocho meses que presentó cuadro clínico consistente en múltiples hospitalizaciones debido a infección por citomegalovirus, endocarditis por Candida albicans e infección recurrente de las vías urinarias por Pseudomonas aeruginosa.El perfil inmunológico mostró disminución del número absoluto de células CD3+ y CD19+, lo que permitió realizar el diagnóstico de inmunodeficiencia combinada severa instaurándose manejo; sin embargo, el niño no se recuperó y falleció.Conclusiones. Las inmunodeficiencias primarias son patologías que requieren una intervención oportuna que permita brindar un mejor pronóstico a los pacientes.

Fourth Update on the Iranian National Registry of Primary Immunodeficiencies: Integration of Molecular Diagnosis

BACKGROUND

The number of inherited diseases and the spectrum of clinical manifestations of primary immunodeficiency disorders (PIDs) are ever-expanding. Molecular diagnosis using genomic approaches should be performed for all PID patients since it provides a resource to improve the management and to estimate the prognosis of patients with these rare immune disorders.

METHOD

The current update of Iranian PID registry (IPIDR) contains the clinical phenotype of newly registered patients during last 5 years (2013-2018) and the result of molecular diagnosis in patients enrolled for targeted and next-generation sequencing.

RESULTS

Considering the newly diagnosed patients (n = 1395), the total number of registered PID patients reached 3056 (1852 male and 1204 female) from 31 medical centers. The predominantly antibody deficiency was the most common subcategory of PID (29.5%). The putative causative genetic defect was identified in 1014 patients (33.1%) and an autosomal recessive pattern was found in 79.3% of these patients. Among the genetically different categories of PID patients, the diagnostic rate was highest in defects in immune dysregulation and lowest in predominantly antibody deficiencies and mutations in the MEFV gene were the most frequent genetic disorder in our cohort.

CONCLUSIONS

During a 20-year registration of Iranian PID patients, significant changes have been observed by increasing the awareness of the medical community, national PID network establishment, improving therapeutic facilities, and recently by inclusion of the molecular diagnosis. The current collective study of PID phenotypes and genotypes provides a major source for ethnic surveillance, newborn screening, and genetic consultation for prenatal and preimplantation genetic diagnosis.

Analysis of differences between total IgG and sum of the IgG subclasses in children with suspected immunodeficiency - indication of determinants

Background

Deficits in disorders of humoral immunity associated with a deficit of antibodies are the most common primary immunodeficiency. Total IgG and IgG subclasses measurements are used to diagnose, differentiate and control in patients with primary and secondary immunodeficiencies.

Methods

The purpose of the study was to analyze the structure patients group according to difference between total IgG and sum of the IgG subclasses and to determine factors affecting the level of this difference. This study was based on data collected from 670 children referred to the Department of Clinical Immunology and Pediatrics in order to diagnose the immune disorders. For all children the level of the total of immunoglobulins IgG and of the IgG subclasses (IgG1, IgG2, IgG3, IgG4) were determined. The group of children was divided into subgroups according to gender, age (under 6 years of age, 6.5–12 years, and 12–18 years), and IgG abnormality (below the normal range, normal and above the normal range). In the patients group, the total IgG values were on average higher than sum of the IgG subclasses.

Results

Statistical analysis shown the all parameters under study (age, gender and IgG abnormality) influence statistically significant on the discrepancy between the sum of the IgG subclasses and total IgG. Assessment of IgG and IgG subclasses levels is based on different methods what causes the discrepancy between the sum of the IgG subclasses and total IgG.

Conclusions

Standardization in that regard is crucial. In addition, we have shown the reliability of the results obtained. Despite the determination in two different laboratories and on different analyzers, as well as the freezing process does not affect the test results.

Deep transcriptome profiling sheds light on key players in nucleus implantation induced immune response in the pearl oyster Pinctada martensii

Immunological rejection of the pearl oysters following nucleus implantation is a major issue limiting the successful rate of cultured pearls. To date, the molecular mechanism of immune tolerance during pearl formation in the pearl oysters is still largely unknown. Through the RNA sequencing platform and comparative transcriptomic analysis, we investigated the chronic gene expression changes at seven time points (0, 5, 10, 15, 20, 30, 60 days post implantation or dpi) over a period of 60 days following nucleus implantation in the pearl oyster Pinctada martensii. A total of 81,390 unique transcripts (or unigenes) with a combined length of 96.8 million bp and a N50 value of 2227 bp were obtained. When compared with sequences in the nr, nt, Swiss-Prot, KEGG, COG and GO databases, 36,380 unigenes can find homologous genes. Pairwise comparison of gene expression among all the samples showed that the largest number (or 6846) of differentially expressed genes was observed at 10 dpi. The number then decreased to below 5000 at 15, 20 and 30 dpi and increased again to 6679 at 60 dpi. PCA analysis further showed that the seven time points can be roughly divided into four groups. Comparative transcriptomic analysis between the four groups identified a variety of genes showing differential expression at different time points, including many immune-related genes such as those encoding for toll-like receptor, lectin, scavenger receptor, and peroxidase. In addition, GO and KEGG enrichment analysis revealed that these differentially expressed genes were mainly associated with metabolism, ribosome function, immune response, signaling transduction, and cytoskeleton organization. Notably, two KEGG pathways, namely "cell adhesion molecules" and "primary immunodeficiency" were significantly enriched during the whole process. This finding indicates that genes in these pathways are likely to play critical roles in the immune tolerance of the pearl oysters. To conclude, the data obtained contribute to a better understanding of the molecular mechanisms of nucleus implantation induced immune response in the pearl oysters, and will facilitate the development of effective measures to improve the performance of pearl culture.

Disease burden for patients with primary immunodeficiency diseases identified at reference hospitals in Guanajuato, Mexico

Background

In addition to the deleterious effect on health, there is considerable economic and psychosocial morbidity associated with primary immunodeficiency diseases (PID). Also, the cost of a late diagnosis frequently results in a heavy disease burden on the patient. The objective of this study was to collect and analyze data on patients with PID in the state of Guanajuato in Mexico, to indirectly estimate the burden of the disease.

Methods

An observational, longitudinal, and comparative study was conducted. A total of 44 patients were included and grouped according to the updated classification of PID.

Results

The median time elapsed from the onset of symptoms to the reference and diagnosis by a tertiary hospital was of 2.17 (IQR = 6.44) years. Before diagnosis, the number of hospitalizations/year per patient was 0.86 (IQR = 2.28), the number of visit to emergency room/year per patient was 0.92 (IQR = 1.77), the number of doctor’s visits/year per patient was 15 (IQR = 11.25), whereas the school/work absence days per patient were reported in 52.72 (IQR = 56.35) days per year. After diagnosis, 20 patients (45.45%) received IVIG replacement therapy, and all of them presented a significant improvement (p <0.05) in all the mentioned variables. Characteristically, even when patients with PID received IVIG, there was still an important disease burden when comparing them against healthy controls. Complications secondary to PID were detected in 19 patients (43.18%). The reported overall mortality rate was 6.82% (n = 3).

Conclusions

We were able to indirectly estimate an important disease burden in patients with PID; which is considered to be preventable, at least in part, with effective interventions like health planning, research, collaboration with primary care providers, and generation of policies and practices, in order to improve the quality of life and care of families with PID.

Diminished plasma levels of common γ-chain cytokines in pulmonary tuberculosis and reversal following treatment

Background

The immune response to tuberculosis (TB) is T cell dependent. T cells are the major facilitators of protection and effector functions with CD4⁺ T cells being the most important players, followed by CD8⁺ T cells. The common γ-chain cytokines IL-2, IL-7, IL-15, and IL-21 play a vital role in peripheral T cell growth and survival. However, the role of common γ-chain cytokines in pulmonary TB (PTB) is poorly understood.

Aim and methods

To examine the association of circulating common γ-chain cytokines with TB disease or infection, we examined the systemic levels of IL-2, IL-7, IL-15, and IL-21 in individuals with PTB, latent TB (LTB) or no TB infection (NTB). We also examined the levels of these cytokines in PTB individuals before and after anti-tuberculosis treatment.

Results

Circulating levels of IL-2, IL-7 and IL-21 were significantly diminished in PTB compared to LTB or NTB individuals. Moreover, TB antigen stimulated whole blood also exhibited diminished levels of common γ-chain cytokines in PTB compared to LTB or NTB individuals. The plasma levels of common γ-chain cytokines exhibited no significant association with the severity or extent of TB disease or with bacterial burdens. However, upon standard anti-TB treatment, both the systemic as well as the TB antigen stimulated levels of IL-2, IL-7 and IL-21 were significantly increased in PTB individuals.

Conclusion

Therefore our data demonstrate that diminished levels of common γ-chain cytokines are a common characteristic of PTB and potentially highlight the importance of boosting these responses to improve treatment outcomes.

Phenotypic and Functional Comparison of Class Switch Recombination Deficiencies with a Subgroup of Common Variable Immunodeficiencies

Primary antibody deficiencies (PADs) are the most common immunodeficiency in humans, characterized by low levels of immunoglobulins and inadequate antibody responses upon immunization. These PADs may result from an early block in B cell development with a complete absence of peripheral B cells and lack of immunoglobulins. In the presence of circulating B cells, some PADs are genetically caused by a class switch recombination (CSR) defect, but in the most common PAD, common variable immunodeficiency (CVID), very few gene defects have as yet been characterized despite various phenotypic classifications. Using a functional read-out, we previously identified a functional subgroup of CVID patients with plasmablasts (PBs) producing IgM only. We have now further characterized such CVID patients by a direct functional comparison with patients having genetically well-characterized CSR defects in CD40L, activation-induced cytidine deaminase (AID) and uracil N-glycosylase activity (UNG). The CSR-like CVID patients showed a failure in B cell activation patterns similar to the classical AID/UNG defects in three out of five CVID patients and distinct more individual defects in the two other CVID cases when tested for cellular activation and PB differentiation. Thus, functional categorization of B cell activation and differentiation pathways extends the expected variation in CVID to CSR-like defects of as yet unknown genetic etiology.

Genetics and immunity in the era of single-cell genomics

Recent developments in the field of single-cell genomics (SCG) are changing our understanding of how functional phenotypes of cell populations emerge from the behaviour of individual cells. Some of the applications of SCG include the discovery of new gene networks and novel cell subpopulations, fine mapping of transcription kinetics, and the relationships between cell clonality and their functional phenotypes. Immunology is one of the fields that is benefiting the most from such advancements, providing us with completely new insights into mammalian immunity. In this review, we start by covering new immunological insights originating from the use of single-cell genomic tools, specifically single-cell RNA-sequencing. Furthermore, we discuss how new genetic study designs are starting to explain inter-individual variation in the immune response. We conclude with a perspective on new multi-omics technologies capable of integrating several readouts from the same single cell and how such techniques might push our biological understanding of mammalian immunity to a new level.

Family Physician Perspectives on Primary Immunodeficiency Diseases

Primary immunodeficiency diseases (PIDs) include over 250 diverse disorders. The current study assessed management of PID by family practice physicians. The American Academy of Allergy, Asthma, and Immunology Primary Immunodeficiency Committee and the Immune Deficiency Foundation conducted an incentivized mail survey of family practice physician members of the American Medical Association and the American Osteopathic Association in direct patient care. Responses were compared with subspecialist immunologist responses from a similar survey. Surveys were returned by 528 (of 4500 surveys mailed) family practice physicians, of whom 44% reported following ≥1 patient with PID. Selective immunoglobulin A deficiency (21%) and chronic granulomatous disease (11%) were most common and were followed by significantly more subspecialist immunologists (P < 0.05). Use of intravenously administered immunoglobulin and live viral vaccinations across PID was significantly different (P < 0.05). Few family practice physicians were aware of professional guidelines for diagnosis and management of PID (4 vs. 79% of subspecialist immunologists, P < 0.05). Family practice physicians will likely encounter patients with PID diagnoses during their career. Differences in how family practice physicians and subspecialist immunologists manage patients with PID underscore areas where improved educational and training initiatives may benefit patient care.

Validity of Primary Immunodeficiency Disease Diagnoses in United States Medicaid Data

PURPOSE

Primary immunodeficiency diseases (PID) are a rare group of disorders with a wide array of clinical presentations. The absence of validated methods to identify these diseases in electronic databases has limited understanding of their epidemiology and the impact of drug therapies on outcomes. We measured the positive predictive values (PPVs) of ICD-9 diagnoses for identifying PID within US Medicaid.

METHODS

We identified Medicaid patients from California, Florida, New York, Ohio, and Pennsylvania with PID ICD-9 diagnoses (common variable immunodeficiency [279.06], X-linked agammaglobulinemia [279.04], hyper-immunoglobulin M syndrome [279.05], Wiskott Aldrich Syndrome [279.12]) recorded at least twice from 1999 to 2007. Outpatient records were reviewed by a clinical immunologist to adjudicate diagnoses. PPVs with 95% confidence intervals (CIs) for confirmed outcomes were determined for individual ICD-9 diagnoses and combinations of diagnoses and Current Procedural Terminology codes for a quantitative immunoglobulin test (82784) or immunoglobulin infusion (96365).

RESULTS

Among 83 patients with PID ICD-9 diagnoses, 16 were adjudicated as having the condition (PPV, 19.3%; 95% CI, 11.4-29.4%). Individual ICD-9 diagnoses had low PPVs (range, 16.7-33.3%). Requiring procedural codes for quantitative immunoglobulins or intravenous immunoglobulin did not increase PPVs of these diagnoses (range, 11.1-41.7%). An X-linked agammaglobulinemia diagnosis plus intravenous immunoglobulin had the highest PPV among the algorithms evaluated (PPV, 41.7%; 95% CI, 15.1-72.3%).

CONCLUSIONS

Algorithms comprising PID ICD-9 diagnoses and procedures for quantitative immunoglobulin tests and immunoglobulin infusion had low PPVs for adjudicated diagnoses in Medicaid. Alternative data sources should be evaluated to study the epidemiology of these diseases.

Evidence-based strategies to reduce intravenous immunoglobulin-induced headaches

OBJECTIVE

To review the literature evaluating pharmacotherapeutic and nonpharmacotherapeutic options available to reduce migraines or headaches associated with intravenous immunoglobulin (IVIG) treatment.

DATA SOURCES

A search of MEDLINE (1946 to February 2015) and other secondary resources was performed using the terms immunoglobulin, immune globulin, intravenous immunoglobulins, migraine, and headache. Other relevant articles referenced from the MEDLINE search were also utilized.

STUDY SELECTION AND DATA EXTRACTION

Data sources were limited to English language clinical trials and case studies. In all, 6 clinical studies and 2 case reports met the criteria.

DATA SYNTHESIS

Headaches or migraines are common adverse effects associated with the administration of IVIG. We evaluated 6 clinical studies and 2 case reports discussing this adverse event in patients treated with IVIG. Strategies used were hydration, switching to an alternate IVIG product, decreased infusion rates, or treating with oral analgesics, opioids, propranolol, sumatriptan, or dihydroergotamines before, during, or after the IVIG infusion. Overall, the majority of patients experienced improvement in headache symptoms, suggesting benefit, after using the various strategies discussed. However, the evidence is limited to case reports and clinical studies with small sample sizes that do not directly measure cause and effect of headache resolution and therapy given in those treated with IVIG.

CONCLUSIONS

An individualized treatment plan consisting of a pharmacotherapy or nonpharmacotherapy strategy used in the literature should be recommended after careful consideration of the patient's condition, specific IVIG product used, history of migraine, and previously failed and successful therapies.

Utility of next generation sequencing in clinical primary immunodeficiencies

Primary immunodeficiencies (PIDs) are a group of genetically heterogeneous disorders that present with very similar symptoms, complicating definitive diagnosis. More than 240 genes have hitherto been associated with PIDs, of which more than 30 have been identified in the last 3 years. Next generation sequencing (NGS) of genomes or exomes of informative families has played a central role in the discovery of novel PID genes. Furthermore, NGS has the potential to transform clinical molecular testing for established PIDs, allowing all PID differential diagnoses to be tested at once, leading to increased diagnostic yield, while decreasing both the time and cost of obtaining a molecular diagnosis. Given that treatment of PID varies by disease gene, early achievement of a molecular diagnosis is likely to enhance treatment decisions and improve patient outcomes.

An educationally inspired illustration of two-dimensional Quantitative Microbiological Risk Assessment (QMRA) and sensitivity analysis

Quantitative Microbiological Risk Assessment (QMRA) is a structured methodology used to assess the risk involved by ingestion of a pathogen. It applies mathematical models combined with an accurate exploitation of data sets, represented by distributions and - in the case of two-dimensional Monte Carlo simulations - their hyperparameters. This research aims to highlight background information, assumptions and truncations of a two-dimensional QMRA and advanced sensitivity analysis. We believe that such a detailed listing is not always clearly presented in actual risk assessment studies, while it is essential to ensure reliable and realistic simulations and interpretations. As a case-study, we are considering the occurrence of listeriosis in smoked fish products in Belgium during the period 2008-2009, using two-dimensional Monte Carlo and two sensitivity analysis methods (Spearman correlation and Sobol sensitivity indices) to estimate the most relevant factors of the final risk estimate. A risk estimate of 0.018% per consumption of contaminated smoked fish by an immunocompromised person was obtained. The final estimate of listeriosis cases (23) is within the actual reported result obtained for the same period and for the same population. Variability on the final risk estimate is determined by the variability regarding (i) consumer refrigerator temperatures, (ii) the reference growth rate of L. monocytogenes, (iii) the minimum growth temperature of L. monocytogenes and (iv) consumer portion size. Variability regarding the initial contamination level of L. monocytogenes tends to appear as a determinant of risk variability only when the minimum growth temperature is not included in the sensitivity analysis; when it is included the impact regarding the variability on the initial contamination level of L. monocytogenes is disappearing. Uncertainty determinants of the final risk indicated the need of gathering more information on the reference growth rate and the minimum growth temperature of L. monocytogenes. Uncertainty in the dose-response relationship was not included in the analysis, hence the level of its influence cannot be assessed in the present research. Finally, a baseline global workflow for QMRA and sensitivity analysis is proposed.

Is murine gammaherpesvirus-68 (MHV-68) a suitable immunotoxicological model for examining immunomodulatory drug-associated viral recrudescence?

Immunosuppressive agents are used for treatment of a variety of autoimmune diseases including rheumatoid arthritis (RA), systemic lupus erythematosis (SLE), and psoriasis, as well as for prevention of tissue rejection after organ transplantation. Recrudescence of herpesvirus infections, and increased risk of carcinogenesis from herpesvirus-associated tumors are related with immunosuppressive therapy in humans. Post-transplant lymphoproliferative disorder (PTLD), a condition characterized by development of Epstein Barr Virus (EBV)-associated B-lymphocyte lymphoma, and Kaposi's Sarcoma (KS), a dermal tumor associated with Kaposi Sarcoma-associated virus (KSHV), may develop in solid organ transplant patients. KS also occurs in immunosuppressed Acquired Immunodeficiency (AIDS) patients. Kaposi Sarcoma-associated virus (KSHV) is a herpes virus genetically related to EBV. Murine gammaherpes-virus-68 (MHV-68) is proposed as a mouse model of gammaherpesvirus infection and recrudescence and may potentially have relevance for herpesvirus-associated neoplasia. The pathogenesis of MHV-68 infection in mice mimics EBV/KSHV infection in humans with acute lytic viral replication followed by dissemination and establishment of persistent latency. MHV-68-infected mice may develop lymphoproliferative disease that is accelerated by disruption of the immune system. This manuscript first presents an overview of gammaherpesvirus pathogenesis and immunology as well as factors involved in viral recrudescence. A description of different types of immunodeficiency then follows, with particular focus on viral association with lymphomagenesis after immunosuppression. Finally, this review discusses different gammaherpesvirus animal models and describes a proposed MHV-68 model to further examine the interplay of immunomodulatory agents and gammaherpesvirus-associated neoplasia.

Clinical and genetic features of 5 Chinese patients with X-linked lymphoproliferative syndrome

In this study, we report the clinical and genetic features of Chinese patients with X-linked lymphoproliferative syndrome (XLP). Male patients with fulminant infectious mononucleosis (FIM), Epstein-Barr virus (EBV)-associated hemophagocytic lymphohistiocytosis (HLH) or persistent EBV viremia were enrolled in this study. Direct sequencing was used to detect SH2D1A/XIAP gene mutations. The patients' clinical features were assessed by retrieval of data from medical records. Twenty-one male patients with FIM, EBV-associated HLH or persistent EBV viremia were evaluated. Four patients had SH2D1A mutations, and one patient had an XIAP mutation. All five of these patients had symptoms of HLH and EBV infection. Among the five patients, the youngest one was only 1 month old at onset. One patient exhibited hypogammaglobulinemia. Of four patients evaluated for immunological function, all exhibited reduced CD4/CD8 ratios. Three patients had rapid disease progression and died. One patient received haematopoietic stem cell transplantation and is well. The overall clinical phenotypes of Chinese patients with XLP matched previous reports. For patients with severe EBV-associated HLH, our results indicate the need to examine the possibility of XLP.

Possible primary immunodeficiency presenting with gastrointestinal symptoms: Case report and minireview

Primary immunodeficiency is a disease characterized by reduced levels of serum immunoglobulins and multiple clinical manifestations. Patients with primary immunodeficiency frequently present with gastrointestinal symptoms, such as diarrhea, malabsorption and weight loss. The mainstay of treatment is replacement therapy with intravenous immunoglobulin (IVIG). In the current study, we report the case of a 23-year-old man with symptoms of chronic diarrhea, malabsorption and weight loss that had been apparent for two years. Subsequent to being diagnosed with possible primary immunodeficiency, the patient was treated with 30 mg/day oral prednisone for one month. The prednisone was then tapered weekly by 5 mg until withdrawal. Three months later, the patient’s clinical symptoms disappeared and his quality of life improved. During the subsequent nine months follow-up, the patient was able to work without suffering any effects from his illness. The body weight of the patient increased and plasma albumin levels were normal. In conclusion, this study describes the case of a patient with primary immunodeficiency-related gastrointestinal symptoms who responded well to oral prednisone treatment.

Primary immunodeficiency diseases at reference and high-specialty hospitals in the state of Guanajuato, Mexico

BACKGROUND

In general, primary immunodeficiency diseases (PIDs) are underdiagnosed in most countries. The objective of this study was to describe the frequency and clinical spectrum of PID in the most important tertiary hospitals in our region.

METHODS

An observational, cross-sectional, with retrospective chart, review study was conducted. A total of 26 patients were included and grouped according to the updated classification of PIDs.

RESULTS

PIDs spectra were as follows: predominantly antibody deficiency diseases were the most common category (65.38%), followed by other well-defined immunodeficiency syndromes (11.55%), congenital defects of phagocyte number and/or function (7.69%), complement deficiencies (3.85%), combined T- and B-cell immunodeficiencies (3.85%), and defects in innate immunity (3.85%). The mean time elapsed from the onset of symptoms to the reference and diagnosis by a tertiary hospital was of 4.65 ± 6.95 years.

CONCLUSIONS

Predominant antibody deficiency disease was the most common group of PIDs, agreeing with international reports. Awareness of underdiagnosis by physicians is crucial for a prompt diagnosis and treatment, which in turn should improve the quality of life among patients with PIDs.

Identification of B cell defects using age-defined reference ranges for in vivo and in vitro B cell differentiation

Primary immunodeficiencies consist to a large extent of B cell defects, as indicated by inadequate Ab levels or response upon immunization. Many B cell defects have not yet been well characterized. Our objective was to create reliable in vivo and in vitro assays to routinely analyze human B cell differentiation, proliferation, and Ig production and to define reference ranges for different age categories. The in vitro assays were applied to classify the developmental and/or functional B cell defects in patients previously diagnosed with common variable immunodeficiency. Apart from standard immunophenotyping of circulating human B cell subsets, an in vitro CFSE dilution assay was used for the assessment of proliferative capacity comparing T cell-dependent and T cell-independent B cell activation. Plasmablast/plasma cell differentiation was assessed by staining for CD20, CD38, and CD138, and measurement of in vitro Ig secretion. At young age, B cells proliferate upon in vitro activation, but neither differentiate nor produce IgG. These latter functions reached adult levels at 5 and 10 y of age for T cell-dependent versus T cell-independent stimulations, respectively. The capacity of B cells to differentiate into plasmablasts and to produce IgG appeared to be contained within the switched memory B cell pool. Using these assays, we could categorize common variable immunodeficiency patients into subgroups and identified a class-switch recombination defect caused by an UNG mutation in one of the patients. We defined age-related reference ranges for human B cell differentiation. Our findings indicate that in vivo B cell functionality can be tested in vitro and helps to diagnose suspected B cell defects.

Comparison of American and European practices in the management of patients with primary immunodeficiencies

Primary immunodeficiency diseases (PIDs) comprise a heterogeneous group of rare disorders. This study was devised in order to compare management of these diseases in the northern hemisphere, given the variability of practice among clinicians in North America. The members of two international societies for clinical immunologists were asked about their management protocols in relation to their PID practice. An anonymous internet questionnaire, used previously for a survey of the American Academy of Allergy, Asthma and Immunology (AAAAI), was offered to all full members of the European Society for Immunodeficiency (ESID). The replies were analysed in three groups, according to the proportion of PID patients in the practice of each respondent; this resulted in two groups from North America and one from Europe. The 123 responses from ESID members (23·7%) were, in the majority, very similar to those of AAAAI respondents, with > 10% of their practice devoted to primary immunodeficiency. There were major differences between the responses of these two groups and those of the general AAAAI respondents whose clinical practice was composed of < 10% of PID patients. These differences included the routine use of intravenous immunoglobulin therapy (IVIg) for particular types of PIDs, initial levels of IVIg doses, dosing intervals, routine use of prophylactic antibiotics, perceptions of the usefulness of subcutaneous immunoglobulin therapy (SCIg) and of the risk to patients' health of policies adopted by health-care funders. Differences in practice were identified and are discussed in terms of methods of health-care provision, which suggest future studies for ensuring continuation of appropriate levels of immunoglobulin replacement therapies.

Neutrophils in innate host defense against Staphylococcus aureus infections

Staphylococcus aureus has been an important human pathogen throughout history and is currently a leading cause of bacterial infections worldwide. S. aureus has the unique ability to cause a continuum of diseases, ranging from minor skin infections to fatal necrotizing pneumonia. Moreover, the emergence of highly virulent, drug-resistant strains such as methicillin-resistant S. aureus in both healthcare and community settings is a major therapeutic concern. Neutrophils are the most prominent cellular component of the innate immune system and provide an essential primary defense against bacterial pathogens such as S. aureus. Neutrophils are rapidly recruited to sites of infection where they bind and ingest invading S. aureus, and this process triggers potent oxidative and non-oxidative antimicrobial killing mechanisms that serve to limit pathogen survival and dissemination. S. aureus has evolved numerous mechanisms to evade host defense strategies employed by neutrophils, including the ability to modulate normal neutrophil turnover, a process critical to the resolution of acute inflammation. Here we provide an overview of the role of neutrophils in host defense against bacterial pathogens and discuss strategies employed by S. aureus to circumvent neutrophil function.

Primary immunodeficiency in children: report of seven years study

BACKGROUND

Primary immunodeficiency diseases (PIDs) are a genetically heterogeneous group of disorders that affect distinct components of the innate and adaptive immune system, such as neutrophils, macrophages, dendritic cells, complement proteins, natural killer cells, T and B lymphocytes. These disorders are rare, with an estimated prevalence of 1:10,000 live births.

OBJECTIVES

This study aimed at describing the clinical features, disease complications, treatment modalities and overall outcome of patients with Primary Immunodeficiency Diseases (PID) in Masih Daneshvari hospital during a 7-year period (2001-2008).

MATERIALS AND METHODS

This was a retrospective study based on the review of patients' medical records. Clinical, laboratory, and epidemiological data including personal and family history were obtained by reviewing records of patients admitted to the Pediatric Pulmonary Ward of NRITLD, a referral center for tuberculosis and lung diseases. The diagnosis was made based on WHO criteria for primary immunodeficiency disorders.

RESULTS

Data collected from 59 patients were evaluated and analyzed. There were 35 (59.3%) males and 24 (40.69%) females. The age of patients ranged from 6 months to 14.5 years and the mean age was 7.4 years. Positive family history was detected in 20 (33.9%) cases and parents of 36 patients (61.2%) were consanguineous. Twenty patients (33.9%) had a family history of PID. Phagocytic disorder (57.2%) was the most common form of PID, followed by antibody deficiency (33.7%) and T-cell or combined deficiency (8.2%). No case of complement deficiency was detected. In this group of under study patients, 2 cases expired as the result of respiratory failure due to drug resistant pneumonia (chronic granulomatous disease cases).

CONCLUSION

Based on studied results, Phagocytic disorders (57.2%) were the most common disorders among our PID patients. This may be due to the large number of CGD patients referred with the pathologic finding of granuloma misdiagnosed with tuberculosis. Considering the high prevalence of PID in this study, cases with unusual, chronic, severe or recurrent infections should be evaluated for immunodeficiency disorders.

CD40/CD40L expression in leukocytes from chronic granulomatous disease patients

Chronic granulomatous disease (CGD) is an inherited disorder caused by defects in the NADPH oxidase complex, which generates superoxide, the precursor of hydrogen peroxide (H(2)O(2)) and other reactive oxygen derivatives with microbicidal activity. Because CGD patients are at risk of chronic inflammatory manifestations, including inflammatory bowel disease and autoimmune diseases, and it is not clear whether these pathologies are exclusively secondary to altered superoxide production, or whether distinct immunologic defects are involved, we explored cell proliferation, lymphocyte cell counts, immunoglobulin levels, presence of autoimmune antibodies and expression of costimulatory molecules in leukocytes from CGD patients. We found that CGD patients have a diminished phytohemagglutinin-induced proliferation of blood mononuclear cells. Following stimulation with PMA plus ionomycin, a reduced percentage of CD40L expression in T lymphocytes and a diminished expression of CD40 molecules in neutrophils were observed on leukocytes from these patients. Our results suggest an altered interplay between elements of innate and adaptive immunity in CGD patients, which may be reflected in an increased susceptibility to opportunistic infections.

Novel purine nucleoside analogues for T-cell-lineage acute lymphoblastic leukaemia and lymphoma

Purine nucleoside phosphorylase (PNP) deficiency is a rare, inherited immunodeficiency disorder in which the specific molecular defect was identified. Clinically, a lack of PNP manifests as profound T-cell deficiency with minor or variable changes in the humoral system. Biochemically, the absence of PNP results in an increase in plasma deoxyguanosine (dGuo) and a T-cell-specific increase in intracellular deoxyguanosine triphosphate (dGTP). This observation has been the impetus for the search for either inhibitors of the enzyme or PNP-resistant dGuo analogues as potential anti-T-cell-lineage agents over the past 30 years. Forodesine (an inhibitor of PNP) and nelarabine (a PNP-resistant dGuo analogue) proved to be T-cell selective when tested in clinic. This review summarises the preclinical, clinical and pharmacokinetic investigations with these novel agents.