Andrew J. Cant

Long-term survival and transplantation of haemopoietic stem cells for immunodeficiencies: report of the European experience 1968–99

BACKGROUND Transplantation of allogeneic haemopoietic stem cells can cure several primary immunodeficiencies. This European report focuses on the long-term results of such procedures done between 1968 and December, 1999, for primary immunodeficiencies. METHODS The report includes data from 37 centres in 18 countries, which participated in a European registry for stem-cell transplantation in severe combined immuno deficiencies (SCID) and in other immunodeficiency disorders (non-SCID). 1082 transplants in 919 patients were studied (566 in 475 SCID patients, 512 in 444 non-SCID patients; four procedures excluded owing to insufficient data). Minimum follow-up of 6 months was required. FINDINGS In SCID, 3-year survival with sustained engraftment was significantly better after HLA-identical than after mismatched transplantation (77% vs 54%; p=0.002) and survival improved over time. In HLA-mismatched stem-cell transplantation, B(-) SCID had poorer prognosis than B(+) SCID. However, improvement with time occurred in both SCID phenotypes. In non-SCID, 3-year survival after genotypically HLA-matched, phenotypically HLA-matched, HLA-mismatched related, and unrelated-donor transplantation was 71%, 42%, 42%, and 59%, respectively (p=0.0006). Acute graft versus host disease predicted poor prognosis whatever the donor origin except in related HLA-identical transplantation in SCID. INTERPRETATION The improvement in survival over time indicates more effective prevention and treatment of disease-related and procedure-related complications--eg, infections and graft versus host disease. An important factor is better prevention of graft versus host disease in the HLA-non-identical setting by use of more efficient methods of T-cell depletion. For non-SCID, stem-cell transplantation can provide a cure, and grafts from unrelated donors are almost as beneficial as those from genetically HLA-identical relatives.

Autoantibodies against IL-17A, IL-17F, and IL-22 in patients with chronic mucocutaneous candidiasis and autoimmune polyendocrine syndrome type I

Most patients with autoimmune polyendocrine syndrome type I (APS-I) display chronic mucocutaneous candidiasis (CMC). We hypothesized that this CMC might result from autoimmunity to interleukin (IL)-17 cytokines. We found high titers of autoantibodies (auto-Abs) against IL-17A, IL-17F, and/or IL-22 in the sera of all 33 patients tested, as detected by multiplex particle-based flow cytometry. The auto-Abs against IL-17A, IL-17F, and IL-22 were specific in the five patients tested, as shown by Western blotting. The auto-Abs against IL-17A were neutralizing in the only patient tested, as shown by bioassays of IL-17A activity. None of the 37 healthy controls and none of the 103 patients with other autoimmune disorders tested had such auto-Abs. None of the patients with APS-I had auto-Abs against cytokines previously shown to cause other well-defined clinical syndromes in other patients (IL-6, interferon [IFN]-γ, or granulocyte/macrophage colony-stimulating factor) or against other cytokines (IL-1β, IL-10, IL-12, IL-18, IL-21, IL-23, IL-26, IFN-β, tumor necrosis factor [α], or transforming growth factor β). These findings suggest that auto-Abs against IL-17A, IL-17F, and IL-22 may cause CMC in patients with APS-I.

IRF8 Mutations and Human Dendritic-Cell Immunodeficiency

BACKGROUND The genetic analysis of human primary immunodeficiencies has defined the contribution of specific cell populations and molecular pathways in the host defense against infection. Disseminated infection caused by bacille Calmette-Guérin (BCG) vaccines is an early manifestation of primary immunodeficiencies, such as severe combined immunodeficiency. In many affected persons, the cause of disseminated BCG disease is unexplained. METHODS We evaluated an infant presenting with features of severe immunodeficiency, including early-onset disseminated BCG disease, who required hematopoietic stem-cell transplantation. We also studied two otherwise healthy subjects with a history of disseminated but curable BCG disease in childhood. We characterized the monocyte and dendritic-cell compartments in these three subjects and sequenced candidate genes in which mutations could plausibly confer susceptibility to BCG disease. RESULTS We detected two distinct disease-causing mutations affecting interferon regulatory factor 8 (IRF8). Both K108E and T80A mutations impair IRF8 transcriptional activity by disrupting the interaction between IRF8 and DNA. The K108E variant was associated with an autosomal recessive severe immunodeficiency with a complete lack of circulating monocytes and dendritic cells. The T80A variant was associated with an autosomal dominant, milder immunodeficiency and a selective depletion of CD11c+CD1c+ circulating dendritic cells. CONCLUSIONS These findings define a class of human primary immunodeficiencies that affect the differentiation of mononuclear phagocytes. They also show that human IRF8 is critical for the development of monocytes and dendritic cells and for antimycobacterial immunity. (Funded by the Medical Research Council and others.).

Osteoclast-poor human osteopetrosis due to mutations in the gene encoding RANKL

Autosomal recessive osteopetrosis is usually associated with normal or elevated numbers of nonfunctional osteoclasts. Here we report mutations in the gene encoding RANKL (receptor activator of nuclear factor–KB ligand) in six individuals with autosomal recessive osteopetrosis whose bone biopsy specimens lacked osteoclasts. These individuals did not show any obvious defects in immunological parameters and could not be cured by hematopoietic stem cell transplantation; however, exogenous RANKL induced formation of functional osteoclasts from their monocytes, suggesting that they could, theoretically, benefit from exogenous RANKL administration.

Phosphoinositide 3-Kinase δ Gene Mutation Predisposes to Respiratory Infection and Airway Damage

Answers from Exomes Exome sequencing, which targets only the protein-coding regions of the genome, has the potential to identify the underlying genetic causes of rare inherited diseases. Angulo et al. (p. 866, published online 17 October; see Perspective by Conley and Fruman) performed exome sequencing of individuals from seven unrelated families with severe, recurrent respiratory infections. The patients carried the same mutation in the gene coding for the catalytic subunit of phosphoinositide 3-kinase δ (PI3Kδ). The mutation caused aberrant activation of this kinase, which plays a key role in immune cell signaling. Drugs inhibiting PI3Kδ are already in clinical trials for other disorders. Gene sequencing of unrelated patients with recurrent airway infections identifies a common underlying mutation. [Also see Perspective by Conley and Fruman] Genetic mutations cause primary immunodeficiencies (PIDs) that predispose to infections. Here, we describe activated PI3K-δ syndrome (APDS), a PID associated with a dominant gain-of-function mutation in which lysine replaced glutamic acid at residue 1021 (E1021K) in the p110δ protein, the catalytic subunit of phosphoinositide 3-kinase δ (PI3Kδ), encoded by the PIK3CD gene. We found E1021K in 17 patients from seven unrelated families, but not among 3346 healthy subjects. APDS was characterized by recurrent respiratory infections, progressive airway damage, lymphopenia, increased circulating transitional B cells, increased immunoglobulin M, and reduced immunoglobulin G2 levels in serum and impaired vaccine responses. The E1021K mutation enhanced membrane association and kinase activity of p110δ. Patient-derived lymphocytes had increased levels of phosphatidylinositol 3,4,5-trisphosphate and phosphorylated AKT protein and were prone to activation-induced cell death. Selective p110δ inhibitors IC87114 and GS-1101 reduced the activity of the mutant enzyme in vitro, which suggested a therapeutic approach for patients with APDS.

Exome sequencing identifies GATA-2 mutation as the cause of dendritic cell, monocyte, B and NK lymphoid deficiency

The human syndrome of dendritic cell, monocyte, B and natural killer lymphoid deficiency presents as a sporadic or autosomal dominant trait causing susceptibility to mycobacterial and other infections, predisposition to myelodysplasia and leukemia, and, in some cases, pulmonary alveolar proteinosis. Seeking a genetic cause, we sequenced the exomes of 4 unrelated persons, 3 with sporadic disease, looking for novel, heterozygous, and probably deleterious variants. A number of genes harbored novel variants in person, but only one gene, GATA2, was mutated in all 4 persons. Each person harbored a different mutation, but all were predicted to be highly deleterious and to cause loss or mutation of the C-terminal zinc finger domain. Because GATA2 is the only common mutated gene in 4 unrelated persons, it is highly probable to be the cause of dendritic cell, monocyte, B, and natural killer lymphoid deficiency. This disorder therefore constitutes a new genetic form of heritable immunodeficiency and leukemic transformation.

Transplantation of hematopoietic stem cells and long-term survival for primary immunodeficiencies in Europe: Entering a new century, do we do better?

BACKGROUND Hematopoietic stem cell transplantation remains the only treatment for most patients with severe combined immunodeficiencies (SCIDs) or other primary immunodeficiencies (non-SCID PIDs). OBJECTIVE To analyze the long-term outcome of patients with SCID and non-SCID PID from European centers treated between 1968 and 2005. METHODS The product-limit method estimated cumulative survival; the log-rank test compared survival between groups. A Cox proportional-hazard model evaluated the impact of independent predictors on patient survival. RESULTS In patients with SCID, survival with genoidentical donors (n = 25) from 2000 to 2005 was 90%. Survival using a mismatched relative (n = 96) has improved (66%), similar to that using an unrelated donor (n = 46; 69%; P = .005). Transplantation after year 1995, a younger age, B(+) phenotype, genoidentical and phenoidentical donors, absence of respiratory impairment, or viral infection before transplantation were associated with better prognosis on multivariate analysis. For non-SCID PID, in contrast with patients with SCID, we confirm that, in the 2000 to 2005 period, using an unrelated donor (n = 124) gave a 3-year survival rate similar to a genoidentical donor (n = 73), 79% for both. Survival was 76% in phenoidentical transplants (n = 23) and worse in mismatched related donor transplants (n = 47; 46%; P = .016). CONCLUSION This is the largest cohort study of such patients with the longest follow-up. Specific issues arise for different patient groups. Patients with B-SCID have worse survival than other patients with SCID, despite improvements in each group. For non-SCID PID, survival is worse than SCID, although more conditions are now treated. Individual disease categories now need to be analyzed so that disease-specific prognosis may be better understood and the best treatments planned.

How dangerous is food allergy in childhood? The incidence of severe and fatal allergic reactions across the UK and Ireland

Aims: To discover the incidence of fatal and severe allergic reactions to food in a large population of children. Methods: A retrospective search for fatalities in children 0–15 years from 1990 to February 1998, primarily of death certification at offices of national statistics. A prospective survey of fatal and severe reactions from March 1998 to February 2000, primarily through the British Paediatric Surveillance Unit. Main outcome measures were deaths and severe reactions. A case was deemed severe if one or more of the following criteria was met: cardiorespiratory arrest; need for inotropic support; fluid bolus >20 ml/kg; more than one dose of epinephrine; more than one dose of nebulised bronchodilator. A case was deemed near fatal if intubation was necessary. Results: The UK under 16 population is 13 million. Over the past 10 years, eight children died (incidence of 0.006 deaths per 100 000 children 0–15 years per year). Milk caused four of the deaths. No child under 13 died from peanut allergy. Two children died despite receiving early epinephrine before admission to hospital; one child with a mild food allergic reaction died from epinephrine overdose. Over the past two years, there were six near fatal reactions (none caused by peanut) and 49 severe ones (10 caused by peanut), yielding incidences of 0.02 and 0.19 per 100 000 children 0–15 years per year respectively. Coexisting asthma is more strongly associated with a severe reaction than the severity of previous reactions. Conclusions: If 5% of the child population have food allergy, the risk that a food allergic child will die from a food allergic reaction is about 1 in 800 000 per year. The food allergic child with asthma may be at higher risk. Prescribing an epinephrine autoinjector requires a careful balance of advantages and disadvantages.

The human syndrome of dendritic cell, monocyte, B and NK lymphoid deficiency

Human immunodeficiency syndrome with loss of DCs, monocytes, and T reg cells; preservation of Langerhans cells; associated loss of BM multilymphoid progenitors; and overproduction of Flt3 ligand.

Early-onset lymphoproliferation and autoimmunity caused by germline STAT3 gain-of-function mutations.

Germline loss-of-function mutations in the transcription factor signal transducer and activator of transcription 3 (STAT3) cause immunodeficiency, whereas somatic gain-of-function mutations in STAT3 are associated with large granular lymphocytic leukemic, myelodysplastic syndrome, and aplastic anemia. Recently, germline mutations in STAT3 have also been associated with autoimmune disease. Here, we report on 13 individuals from 10 families with lymphoproliferation and early-onset solid-organ autoimmunity associated with 9 different germline heterozygous mutations in STAT3. Patients exhibited a variety of clinical features, with most having lymphadenopathy, autoimmune cytopenias, multiorgan autoimmunity (lung, gastrointestinal, hepatic, and/or endocrine dysfunction), infections, and short stature. Functional analyses demonstrate that these mutations confer a gain-of-function in STAT3 leading to secondary defects in STAT5 and STAT1 phosphorylation and the regulatory T-cell compartment. Treatment targeting a cytokine pathway that signals through STAT3 led to clinical improvement in 1 patient, suggesting a potential therapeutic option for such patients. These results suggest that there is a broad range of autoimmunity caused by germline STAT3 gain-of-function mutations, and that hematologic autoimmunity is a major component of this newly described disorder. Some patients for this study were enrolled in a trial registered at www.clinicaltrials.gov as #NCT00001350.