A significant number of contributions to our understanding of primary immunodeficiencies (PIDs) in pathogenesis, diagnosis, and treatment were published in the Journal in 2013. For example, deficiency of mast cell degranulation caused by signal transducer and activator of transcription 3 deficiency was demonstrated to contribute to the difference in the frequency of severe allergic reactions in patients with autosomal dominant hyper-IgE syndrome compared with that seen in atopic subjects with similar high IgE serum levels. High levels of nonglycosylated IgA were found in patients with Wiskott-Aldrich syndrome, and these abnormal antibodies might contribute to the nephropathy seen in these patients. New described genes causing immunodeficiency included caspase recruitment domain 11 (CARD11), mucosa-associated lymphoid tissue 1 (MALT1) for combined immunodeficiencies, and tetratricopeptide repeat domain 7A (TTC7A) for mutations associated with multiple atresia with combined immunodeficiency. Other observations expand the spectrum of clinical presentation of specific gene defects (eg, adult-onset idiopathic T-cell lymphopenia and early-onset autoimmunity might be due to hypomorphic mutations of the recombination-activating genes). Newborn screening in California established the incidence of severe combined immunodeficiency at 1 in 66,250 live births. The use of hematopoietic stem cell transplantation for PIDs was reviewed, with recommendations to give priority to research oriented to establish the best regimens to improve the safety and efficacy of bone marrow transplantation. These represent only a fraction of significant research done in patients with PIDs that has accelerated the quality of care of these patients. Genetic analysis of patients has demonstrated multiple phenotypic expressions of immune deficiency in patients with nearly identical genotypes, suggesting that additional genetic factors, possibly gene dosage, or environmental factors are responsible for this diversity.
Basic and clinical immunology articles published in the Journal in 2012 were mostly related to the expanding area of primary immunodeficiencies (PIDs). Novel forms of PID were identified by using whole-exome sequencing or after careful examination of flow cytometric data, as in the reports of lymphocyte-specific protein tyrosine kinase, CD27, and CD21 deficiencies. Absent IgG and IgA memory B cells were described in patients with hyper-IgE syndrome, which is consistent with defective antibody response and suggests a potential benefit of immunoglobulin replacement. Impaired production of antibodies to polysaccharide antigens by the human B-cell subset analog to murine B-1 cells was reported in a child with selective polysaccharide antibody deficiency. Increased production of inflammatory cytokines by monocyte-derived cells on Toll-like receptor activation was reported in patients with X-linked agammaglobulinemia, underscoring the important role of Bruton tyrosine kinase in modulation of inflammation. The mechanisms explaining susceptibility to yeast infections and development of chronic mucocutaneous candidiasis were extensively studied. Universal newborn screening for T-cell deficiencies is being implemented in several states, resulting in the diagnosis of a higher number of immunodeficient newborns than previously estimated. The use of laboratory testing to distinguish PIDs from HIV infection was clarified. In the management of PIDs, refinement of indication and strategies to hematopoietic stem cell transplantation resulted in improved outcomes. The use of anti-IL-6 mAbs showed promise as an alternative treatment in patients with Schnitzler syndrome.
Investigations of basic immunologic mechanisms and clinical studies of primary immunodeficiencies were most prevalent in 2011. Significant progress was achieved in the characterization of T(H)17 cell differentiation and associated cytokines in the setting of inflammatory disorders, HIV infection, and immunodysregulation disorders. The role of transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI) mutations in the pathogenesis of CVID was further described and reported to be likely mediated by impaired TACI expression affecting B-cell function. The frequency of autoimmunity in patients with partial DiGeorge syndrome was estimated at 8.5%, predominantly resulting in blood cytopenias and hypothyroidism. Several reports emphasized the presentation of neoplasias, most often lymphomas, as the first manifestation of several primary immunodeficiencies. Novel strategies for newborn screening of B-cell lymphopenia by measuring immunoglobulin ? chain-deletion recombinant excision circles and for adenosine deaminase deficiency using tandem mass spectrometry were demonstrated to be feasible at a large scale. Progress in the treatment of primary immunodeficiencies included increased success with unrelated HLA-compatible donors for hematopoietic stem cell transplantation and the development of new gene therapy approaches with improved safety features. Induced pluripotent stem cells were developed from patients with primary immunodeficiencies, providing a virtually unlimited resource for pathophysiology and gene correction studies. New findings in several of the uncommon immunodeficiencies, such as the increased susceptibility to severe viral infections caused by defects in the activation of the Toll-like receptor 3 pathway, overall contributed to the understanding of their immunologic basis and provided for the design of effective diagnostic and therapeutic strategies.
Matched related donor (MRD) hematopoietic stem cell transplantation (HSCT) is a successful treatment for chronic granulomatous disease (CGD), but the safety and efficacy of HSCT from unrelated donors is less certain.
Reports in basic and clinical immunology in 2010 reflected the use of state-of-the-art genetic and immunologic tools to characterize the pathogenesis of immunologic diseases and the development of novel therapies directed to these conditions. B-cell biology has been explained in greater detail, significantly with lessons from the genetic defects found in the humoral immunodeficiencies. Therapeutic mAbs are given for an increasing number of indications, such as anti-CD20 antibodies or rituximab, which was initially developed for non-Hodgkin lymphomas and is currently used in diverse autoimmune and inflammatory disorders. The report of an infant with severe combined immunodeficiency (SCID) in Massachusetts detected by means of newborn screening and successfully treated with hematopoietic stem cell transplantation validated recent efforts toward newborn screening for SCID. Improvement of survival outcomes for patients with primary immunodeficiencies treated with hematopoietic stem cell transplantation was demonstrated in a large European cohort, with significant appreciation of the type of donor graft, particularly the use of HLA-matched unrelated donors for patients with non-SCID. Progress in cellular mechanisms of drug hypersensitivity included the characterization of nitroso-modified drug metabolites as potent T-cell activators and the identification of the relocation of plasmacytoid dendritic cells from blood to skin as a potential risk factor for reactivation of viral disease.
Heterozygous deleterious mutations in the gene encoding the tumor necrosis factor receptor superfamily member 13b (TNFRSF13B), or transmembrane activator and CAML interactor (TACI), have been associated with the development of common variable immunodeficiency. Smith-Magenis syndrome (SMS) is a genetic disorder characterized by developmental delay, behavioral disturbances, craniofacial anomalies, and recurrent respiratory tract infections. Eighty percent of subjects have a chromosome 17p11.2 microdeletion, which includes TACI. The remaining subjects have mutations sparing this gene.
The contribution of B cells to the pathology of Omenn syndrome and leaky severe combined immunodeficiency (SCID) has not been previously investigated. We have studied a mut/mut mouse model of leaky SCID with a homozygous Rag1 S723C mutation that impairs, but does not abrogate, V(D)J recombination activity. In spite of a severe block at the pro-B cell stage and profound B cell lymphopenia, significant serum levels of immunoglobulin (Ig) G, IgM, IgA, and IgE and a high proportion of Ig-secreting cells were detected in mut/mut mice. Antibody responses to trinitrophenyl (TNP)-Ficoll and production of high-affinity antibodies to TNP-keyhole limpet hemocyanin were severely impaired, even after adoptive transfer of wild-type CD4(+) T cells. Mut/mut mice produced high amounts of low-affinity self-reactive antibodies and showed significant lymphocytic infiltrates in peripheral tissues. Autoantibody production was associated with impaired receptor editing and increased serum B cell-activating factor (BAFF) concentrations. Autoantibodies and elevated BAFF levels were also identified in patients with Omenn syndrome and leaky SCID as a result of hypomorphic RAG mutations. These data indicate that the stochastic generation of an autoreactive B cell repertoire, which is associated with defects in central and peripheral checkpoints of B cell tolerance, is an important, previously unrecognized, aspect of immunodeficiencies associated with hypomorphic RAG mutations.
High-resolution melting analysis was applied to X-linked chronic granulomatous disease, a rare disorder resulting from mutations in CYBB. Melting curves of the 13 PCR products bracketing CYBB exons were predicted by Polands algorithm and compared with observed curves from 96 normal individuals. Primer plates were prepared robotically in batches and dried, greatly simplifying the 3- to 6-hour workflow that included DNA isolation, PCR, melting, and cycle sequencing of any positive products. Small point mutations or insertions/deletions were detected by mixing the hemizygous male DNA with normal male DNA to produce artificial heterozygotes, whereas detection of gross deletions was performed on unmixed samples. Eighteen validation samples and 22 clinical kindreds were analyzed for CYBB mutations. All blinded validation samples were correctly identified. The clinical probands were identified after screening for neutrophil oxidase activity. Nineteen different mutations were found, including seven near intron-exon boundaries predicting splicing defects, five substitutions within exons, three small deletions predicting premature termination, and four gross deletions of multiple exons. Ten novel mutations were found, including (c.) two missense (730T>A, 134T>G), one nonsense (90C>A), four splice site defects (45 + 1G>T, 674 + 4A>G, 1461 + 2delT, and 1462-2A>C), two small deletions (636delT, 1661_1662delCT), and one gross deletion of exons 6 to 8. High-resolution melting can provide timely diagnosis at low cost for effective clinical management of rare, genetic primary immunodeficiency disorders.
Development of the field of organ and tissue transplantation has accelerated remarkably since the human MHC was discovered in 1967. Matching of donor and recipient for MHC antigens has been shown to have a significant positive effect on graft acceptance. The roles of the different components of the immune system involved in the tolerance or rejection of grafts and in graft-versus-host disease have been clarified. These components include antibodies, antigen-presenting cells, helper and cytotoxic T-cell subsets, immune cell-surface molecules, signaling mechanisms, and cytokines. The development of pharmacologic and biological agents that interfere with the alloimmune response has had a crucial role in the success of organ transplantation. Combinations of these agents work synergistically, leading to lower doses of immunosuppressive drugs and reduced toxicity. Reports of significant numbers of successful solid-organ transplantations include those of the kidneys, liver, heart, and lung. The use of bone marrow transplantation for hematologic diseases, particularly hematologic malignancies and primary immunodeficiencies, has become the treatment of choice in many of these conditions. Other sources of hematopoietic stem cells are also being used, and diverse immunosuppressive drug regimens of reduced intensity are being proposed to circumvent the mortality associated with the toxicity of these drugs. Gene therapy to correct inherited diseases by means of infusion of gene-modified autologous hematopoietic stem cells has shown efficacy in 2 forms of severe combined immunodeficiency, providing an alternative to allogeneic tissue transplantation.
In 2009, reports on basic and clinical immunology had an increased focus on human disease mechanisms and management. The molecular pathogenesis of familial angioedema associated with estrogen was further explored to find possible factors affecting severity, including polymorphisms in enzymes and receptors related to bradykinin pathways. A placebo-controlled clinical trial of C1 esterase inhibitor concentrate in patients with hereditary angioedema demonstrated the safety of its use and its efficacy to reduce the duration of angioedema attacks. The interaction of innate immunity and adaptive responses was further examined in several reports, establishing the significant role of Toll-like receptor stimulation for the development of optimal specific antibody responses. The 2009 update of the classification of primary immunodeficiencies introduced more than 15 new genetic defects related to the immune response, including of dedicator of cytokinesis 8 (DOCK8) mutations, which are responsible for the autosomal recessive form of the hyper-IgE syndrome. Other reports expanded the clinical spectrum of disease and improved the characterization of conditions such as warts, hypogammaglobulinemia, and myelokathexis syndrome or the occurrence of mucormycosis and Serratia species infections in patients with chronic granulomatous disease. The frequent presentation of gastrointestinal disorders in patients with humoral immunodeficiencies was recognized, and recommendations for management were reviewed. Clinical research focused on severe combined immunodeficiency included the development and implementation of a state-wide newborn screening program for this condition, a desired goal considering the significant reduction of mortality rate when the diagnosis is made early before opportunistic infections occur.
There are an expanding number of primary immunodeficiency diseases (PIDDs), each associated with unique diagnostic and therapeutic complexities. Limited data, however, exist supporting specific therapeutic interventions. Thus, a survey of PIDD management was administered to allergists/immunologists in the United States to identify current perspectives and practices. Among 405 respondents, the majority of key management practices identified were consistent with existing data and guidelines, including the provision of immunoglobulin therapy, immunoglobulin dosing and selective avoidance of live viral vaccines. Practices for which there are little specific data or evidence-based guidance were also examined, including evaluation of IgG trough levels for patients receiving immunoglobulin, use of prophylactic antibiotics and recommendations for complementary/alternative medicine. Here, variability applied to PIDD patients was identified. Differences between practitioners clinically focused upon PIDD and general allergists/immunologists were also identified. Thus, a need for expanded clinical research in PIDD to optimize management and potentially improve outcomes was defined.
Extrinsic factors can adversely affect immune responses, producing states of secondary immunodeficiency and consequent increased risk of infections. These immunodeficiencies, which can be encountered in routine clinical practice, arise from a number of conditions, such as treatment with glucocorticoids and immunomodulatory drugs, surgery and trauma, extreme environmental conditions, and chronic infections, such as those caused by HIV. The most common cause of immunodeficiency is malnutrition, affecting many communities around the world with restricted access to food resources. Protein-calorie deficiency and micronutrient deficiencies have been shown to alter immune responses; of note, recent progress has been made in the influence of vitamin D deficiency in causing failure of immune activation. Other categories of disease that might present with secondary immunodeficiency include metabolic diseases and genetic multisystemic syndromes. The immune defects observed in secondary immunodeficiency are usually heterogeneous in their clinical presentation, and their prognosis depends on the severity of the immune defect. Management of the primary condition often results in improvement of the immunodeficiency; however, this is sometimes not possible, and the risk of infections can be reduced with prompt antimicrobial treatment and prophylaxis.
The effect of pretransplantation conditioning on the long-term outcomes of patients receiving hematopoietic stem cell transplantation for severe combined immunodeficiency (SCID) has not been completely determined.
The immune system consists of a diverse array of immunocompetent cells and inflammatory mediators that exist in complex networks. These components interact through cascades and feedback circuits, maintaining physiologic inflammation (eg, tissue repair) and immunosurveillance. In various autoimmune and allergic diseases, a foreign antigen or autoantigen might upset this fine balance, leading to dysregulated immunity, persistent inflammation, and ultimately pathologic sequelae. In recent years, there has been tremendous progress delineating the specific components of the immune system that contribute to various aspects of normal immunity and specific disease states. With this greater understanding of pathogenesis coupled with advances in biotechnology, many immunomodulatory agents commonly called "biologic agents" have been introduced into the clinic for the treatment of various conditions, including immune globulins and cytokines. The 2 most common classes of approved biologic agents are mAbs and fusion proteins with exquisite specificity. These agents have the potential both to optimize outcomes through more thorough modulation of specific parts of the dysregulated immune response and to minimize toxicity compared with less specific methods of immunosuppression.
We reviewed selected reports in the field of basic and clinical immunology published in 2008. Research progress in the immunologic mechanisms of allergic disease included the modulation of T(H)2 responses by specific transcription factors and receptors associated with the innate immunity, underscoring the importance of the interactions between adaptive and innate immune mechanisms. Investigations of the pathophysiology of hereditary angioedema included a variety of host factors with roles in bradykinin metabolism and vasomotor activity, explaining the variable severity of the clinical presentation. The research focus in HIV infection has shifted from control of disease progression to the barriers for viral eradication, and the search for vaccine designs that provide immunity in the short window between infection and establishment of viral reservoirs. HIV-infected individuals who receive antiviral treatment develop a high incidence of asthma, resembling the inflammatory processes associated with immunoreconstitution. The correlation of molecular diagnosis and clinical presentation was analyzed in 4 relatively rare primary immunodeficiencies: hyper-IgE syndrome; immune dysfunction, polyendocrinopathy, enteropathy, X-linked disease; cartilage-hair hypoplasia; and nuclear factor-kappaB essential modulator deficiency. Studies of patients with partial DiGeorge syndrome and chronic granulomatous disease unveiled subclinical deficiencies that might have an impact in their care. Long-term outcomes from patients with severe combined immunodeficiency who received bone marrow transplants were considered successful compared with the alternative of no intervention. However, the occurrence of adverse events reinforces the need for coordinate efforts to develop optimal protocols for hematopoietic stem cell transplantation for severe immune defects.
A major diagnostic intervention in the consideration of many patients suspected to have primary immunodeficiency diseases (PIDDs) is the application and interpretation of vaccination. Specifically, the antibody response to antigenic challenge with vaccines can provide substantive insight into the status of human immune function. There are numerous vaccines that are commonly used in healthy individuals, as well as others that are available for specialized applications. Both can potentially be used to facilitate consideration of PIDD. However, the application of vaccines and interpretation of antibody responses in this context are complex. These rely on consideration of numerous existing specific studies, interpolation of data from healthy populations, current diagnostic guidelines, and expert subspecialist practice. This document represents an attempt of a working group of the American Academy of Allergy, Asthma & Immunology to provide further guidance and synthesis in this use of vaccination for diagnostic purposes in consideration of PIDD, as well as to identify key areas for further research.
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