Alan P. Knutsen

Allergic Bronchopulmonary Aspergillosis in Cystic Fibrosis—State of the Art: Cystic Fibrosis Foundation Consensus Conference

Because of the difficulties of recognizing allergic bronchopulmonary aspergillosis (ABPA) in the context of cystic fibrosis (because of overlapping clinical, radiographic, microbiologic, and immunologic features), advances in our understanding of the pathogenesis of allergic aspergillosis, new possibilities in therapy, and the need for agreed-upon definitions, an international consensus conference was convened. Areas addressed included fungal biology, immunopathogenesis, insights from animal models, diagnostic criteria, epidemiology, the use of new immunologic and genetic techniques in diagnosis, imaging modalities, pharmacology, and treatment approaches. Evidence from the existing literature was graded, and the consensus views were synthesized into this document and recirculated for affirmation. Virulence factors in Aspergillus that could aggravate these diseases, and particularly immunogenetic factors that could predispose persons to ABPA, were identified. New information has come from transgenic animals and recombinant fungal and host molecules. Diagnostic criteria that could provide a framework for monitoring were adopted, and helpful imaging features were identified. New possibilities in therapy produced plans for managing diverse clinical presentations.

Fungi and allergic lower respiratory tract diseases

Asthma is a common disorder that in 2009 afflicted 8.2% of adults and children, 24.6 million persons, in the United States. In patients with moderate and severe persistent asthma, there is significantly increased morbidity, use of health care support, and health care costs. Epidemiologic studies in the United States and Europe have associated mold sensitivity, particularly to Alternaria alternata and Cladosporium herbarum, with the development, persistence, and severity of asthma. In addition, sensitivity to Aspergillus fumigatus has been associated with severe persistent asthma in adults. Allergic bronchopulmonary aspergillosis (ABPA) is caused by A fumigatus and is characterized by exacerbations of asthma, recurrent transient chest radiographic infiltrates, coughing up thick mucus plugs, peripheral and pulmonary eosinophilia, and increased total serum IgE and fungus-specific IgE levels, especially during exacerbation. The airways appear to be chronically or intermittently colonized by A fumigatus in patients with ABPA. ABPA is the most common form of allergic bronchopulmonary mycosis (ABPM); other fungi, including Candida, Penicillium, and Curvularia species, are implicated. The characteristics of ABPM include severe asthma, eosinophilia, markedly increased total IgE and specific IgE levels, bronchiectasis, and mold colonization of the airways. The term severe asthma associated with fungal sensitization (SAFS) has been coined to illustrate the high rate of fungal sensitivity in patients with persistent severe asthma and improvement with antifungal treatment. The immunopathology of ABPA, ABPM, and SAFS is incompletely understood. Genetic risks identified in patients with ABPA include HLA association and certain T(H)2-prominent and cystic fibrosis variants, but these have not been studied in patients with ABPM and SAFS. Oral corticosteroid and antifungal therapies appear to be partially successful in patients with ABPA. However, the role of antifungal and immunomodulating therapies in patients with ABPA, ABPM, and SAFS requires additional larger studies.

Transplantation Outcomes for Severe Combined Immunodeficiency, 2000–2009

BACKGROUND The Primary Immune Deficiency Treatment Consortium was formed to analyze the results of hematopoietic-cell transplantation in children with severe combined immunodeficiency (SCID) and other primary immunodeficiencies. Factors associated with a good transplantation outcome need to be identified in order to design safer and more effective curative therapy, particularly for children with SCID diagnosed at birth. METHODS We collected data retrospectively from 240 infants with SCID who had received transplants at 25 centers during a 10-year period (2000 through 2009). RESULTS Survival at 5 years, freedom from immunoglobulin substitution, and CD3+ T-cell and IgA recovery were more likely among recipients of grafts from matched sibling donors than among recipients of grafts from alternative donors. However, the survival rate was high regardless of donor type among infants who received transplants at 3.5 months of age or younger (94%) and among older infants without prior infection (90%) or with infection that had resolved (82%). Among actively infected infants without a matched sibling donor, survival was best among recipients of haploidentical T-cell-depleted transplants in the absence of any pretransplantation conditioning. Among survivors, reduced-intensity or myeloablative pretransplantation conditioning was associated with an increased likelihood of a CD3+ T-cell count of more than 1000 per cubic millimeter, freedom from immunoglobulin substitution, and IgA recovery but did not significantly affect CD4+ T-cell recovery or recovery of phytohemagglutinin-induced T-cell proliferation. The genetic subtype of SCID affected the quality of CD3+ T-cell recovery but not survival. CONCLUSIONS Transplants from donors other than matched siblings were associated with excellent survival among infants with SCID identified before the onset of infection. All available graft sources are expected to lead to excellent survival among asymptomatic infants. (Funded by the National Institute of Allergy and Infectious Diseases and others.).

Allergic Bronchopulmonary Aspergillosis in Asthma and Cystic Fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a Th2 hypersensitivity lung disease in response to Aspergillus fumigatus that affects asthmatic and cystic fibrosis (CF) patients. Sensitization to A. fumigatus is common in both atopic asthmatic and CF patients, yet only 1-2% of asthmatic and 7–9% of CF patients develop ABPA. ABPA is characterized by wheezing and pulmonary infiltrates which may lead to pulmonary fibrosis and/or bronchiectasis. The inflammatory response is characterized by Th2 responses to Aspergillus allergens, increased serum IgE and eosinophilia. A number of genetic risks have recently been identified in the development of ABPA. These include HLA-DR and HLA-DQ, IL-4 receptor alpha chain (IL-4RA) polymorphisms, IL-10-1082GA promoter polymorphisms, surfactant protein A2 (SP-A2) polymorphisms, and cystic fibrosis transmembrane conductance regulator gene (CFTR) mutations. The studies indicate that ABPA patients are genetically at risk to develop skewed and heightened Th2 responses to A. fumigatus antigens. These genetic risk studies and their consequences of elevated biologic markers may aid in identifying asthmatic and CF patients who are at risk to the development of ABPA. Furthermore, these studies suggest that immune modulation with medications such as anti-IgE, anti-IL-4 and/or IL-13 monoclonal antibodies may be helpful in the treatment of ABPA.

Umbilical cord blood transplantation in severe T-cell immunodeficiency disorders: two-year experience.

Hematopoietic stem cell transplantation is the treatment of choice for severe primary T-cell immunodeficiencies. When an HLA-identical sibling as the donor is not available, an alternative donor stem cell source is needed. In primary T-cell immunodeficiencies, T-cell-depleted HLA-haploidentical bone marrow transplantation has been particularly successful in reconstituting the immune system in many but not all of the severe T-cell immune deficiency disorders. This study reports the use of umbilical cord blood (UCB) stem cell transplantation in severe T-cell immune deficiency.Umbilical cord blood was evaluated as a stem cell source for immune reconstitution in children with severe primary T-cell immunodeficiency disorders, such as severe combined immunodeficiency syndrome (SCID), reticular dysgenesis, thymic dysplasia, combined immunodeficiency disease (CID), and Wiskott–Aldrich syndrome (WAS) when a matched sibling donor was unavailable. From 1/96 through 5/98, eight children received unrelated cord blood stem cell transplantation following a preparative regimen for the treatment of combined immunodeficiency diseases. The patients ranged in age from 2 weeks to 8 years. The cord blood units were 3/6 HLA antigen matches in two children, 4/6 in four children, and 5/6 in two child, with molecular HLA-DR mismatch in three of the children. The average time for neutrophil engraftment (absolute neutrophil count >500/mm3) was 12 days (range 10–15 days) and the average time for platelet engraftment (platelet count >20,000/mm3) was 36 days (range 24–50 days). A patient with reticular dysgenesis failed to engraft following her first transplant, but fully engrafted after a second unrelated donor cord blood transplantation. Five of six patients exhibited grade I graft-versus-host disease (GvHD), while one child had grade IV skin and gut GvHD. Immunologic reconstitution demonstrated that cord blood stem cell transplantation resulted in consistent and stable T-, B- and natural killer (NK) cell development. The kinetics of development were such that T-cell development occurred between 60 to 100 days. Initial T-cell engraftment consisted predominantly of CD45RO+, CD3+, and CD4+ T cells, and at 12 to 24 months changed to CD45RA+, CD3+, and CD4+ T cells, indicatingde novomaturation of T cells. NK cell development occurred at approximately 180 days. B cells engrafted early, and study of functional B-cell antibody responses revealed that five of six patients in whom intravenous immune globulin has been discontinued have low detectable antibody responses to tetanus and diphtheria toxoid immunizations at 18 to 24 months posttransplantation.Unrelated umbilical donor cord blood is an alternative source of stem cells for transplantation in children with severe T-cell immune deficiency disorders when a suitable HLA-matched donor is not available and when a T-depleted haploidentical preparation is not beneficial. Benefits of UCB include rapid and reliable recovery of immune function, low risk of GvHD, and low viral transmission rate.

IgE antibody to Aspergillus fumigatus recombinant allergens in cystic fibrosis patients with allergic bronchopulmonary aspergillosis

Background:  Allergic bronchopulmonary aspergillosis (ABPA) in cystic fibrosis (CF) is characterized by a heightened Th2 CD4+ T‐cell response to Aspergillus fumigatus (Af) allergens and a hyper‐immunoglobulin E (IgE) state compared with cystic fibrosis patients without ABPA. The IgE serologic differentiation of ABPA from atopic CF patients can be difficult. We propose as the reactivity with purified antigens varies qualitatively and quantitatively and that the antibody response is more specific than with crude Af antigen extract, the IgE responses to purified recombinant Af allergens may differentiate ABPA from atopic CF patients.

Thymosin-α1 stimulates maturation of CD34+ stem cells into CD3+4+ cells in an in vitro thymic epithelia organ coculture model

The effect of thymosin-alpha1 on thymopoiesis is largely unknown. Thymosin is found in the cortical and medullary thymic epithelia, as well as in nurse cells; thus, it is hypothesized that thymosin may affect both early and late stage of thymocyte maturation. In this study, the effect of thymosin-alpha1 on thymopoiesis was determined by coculturing in vitro CD34+ stem cells (SC) with allogeneic cultured thymic epithelia fragments (CTEF) for 1-4 weeks and analyzing T-cell maturation by flow cytometry. Thymosin-alpha1 significantly enhanced the cell number (e.g., proliferation) of mononuclear cells obtained at 2 and 4 weeks of the SC-CTEF cocultures (P < 0.01 and < 0.05, respectively). In particular, thymosin-alpha1 stimulated expression of CD3+ cells at 3 and 4 weeks (P < 0.05). The predominant subpopulation increased by thymosin stimulation was single positive mature CD4+ cells, which was confirmed to occur within the SC-CTEF thymic organ tissue by laser confocal immunofluorescence microscopy. Thymosin stimulation tended to enhance IL-7 synthesis, critical cytokine in the maturation of thymocytes. In summary, this is the first study to demonstrate that thymosin-alpha1 enhanced thymopoiesis of CD34+ stem cells in humans using an in vitro model of differentiation using stem cells and cultured thymic epithelial fragments cocultures. Furthermore, the thymosin significantly increased expression of CD3+4+ T cells.

IL-4 alpha chain receptor (IL-4Rα) polymorphisms in allergic bronchopulmonary sspergillosis

BackgroundAllergic bronchopulmonary aspergillosis occurs in 7–10% of cystic fibrosis (CF) and 1–2% of asthmatic patients. HLA-DR restriction and increased sensitivity to IL-4 stimulation have been proposed as risk factors in these populations.ObjectiveWe examined for the presence of IL-4 receptor alpha chain (IL-4Rα) single nucleotide polymorphisms (SNPs) in ABPA and whether these accounted for increased sensitivity to IL-4 stimulation.MethodsOne extracellular (ile75val) and four cytoplasmic IL-4Rα SNPs were analyzed in 40 CF and 22 asthmatic patients and in 56 non-ABPA CF and asthmatic patients. Sensitivity to IL-4 stimulation was measured by induction of CD23 expression on B cells.ResultsIL-4Rα SNPs were observed in 95% of ABPA patients. The predominant IL-4Rα SNP was the extracellular IL-4Rα SNP, ile75val, observed in 80% of ABPA patients.ConclusionThe presence of IL-4Rα SNPs, principally ile75val, appears to be a genetic risk for the development of ABPA.

Patients with IgG subclass and/or selective antibody deficiency to polysaccharide antigens: Initiation of a controlled clinical trial of intravenous immune globulin

Selective IgG subclass deficiencies and/or selectively impaired antibody responses to bacterial capsular polysaccharide antigens have been increasingly reported. In this report, 13 children with recurrent infections and deficient antibody responses to polysaccharide antigens are described. Serum IgG2 subclass concentrations were normal in all the patients, and two children had low IgG3 levels. Mean serum antibody concentrations to the capsular polysaccharide antigens of Streptococcus pneumoniae and Haemophilus influenzae were significantly decreased after immunizations, but antibody responses to diphtheria and tetanus toxoids were normal. The identification of children with selective antibody deficiencies and recurrent infections has prompted a multicenter, double-blind, placebo-controlled study to evaluate the efficacy and safety of intravenous immune globulin therapy in these patients.

Immunopathogenesis of allergic bronchopulmonary aspergillosis in cystic fibrosis

Allergic bronchopulmonary aspergillosis (ABPA) is a hypersensitivity lung disease mediated by an allergic late-phase inflammatory response to Aspergillus fumigatus antigens. ABPA is characterized by markedly elevated Aspergillus-specific and total IgE levels and eosinophilia, and manifested by wheezing, pulmonary infiltrates, and bronchiectasis and fibrosis, which afflict asthmatic and cystic fibrosis (CF) patients. We propose that ABPA develops in genetically susceptible CF patients due to HLA-DR2 and DR5 restriction, increased sensitivity to IL-4 stimulation, and increased A. fumigatus allergen-specific Th2 CD4+ T-cell-mediated responses. In addition, A. fumigatus proteases play a role in facilitation of antigen transport across the epithelial cell layer by damaging the epithelial integrity and by a direct interaction with epithelial cell surface receptors, resulting in pro-inflammatory cytokine production and corresponding inflammatory responses.