Allergen immunotherapy is the only recognized treatment of allergic disease that can both ameliorate symptoms and alter the natural course of the allergic disease [1, 2]. The efficacy of allergen immunotherapy has been proven through well-conducted double-blind placebo-controlled trials involving patients with rhinitis, asthma and anaphylaxis. Although the exact mechanism of action of immunotherapy is not known, its allergen specificity and clinical effectiveness within different allergic diseases make it an attractive (and possibly unique) therapy. The drawbacks of allergen immunotherapy relate to its safety profile, compliance and possibly cost. It was noted by Noon [3] in 1911 that in the early stages of ‘immunization’, some individuals may manifest a severe attack of hayfever. Although adverse reactions to allergen immunotherapy and allergen skin prick testing were recognized in the latter half of the last century, it was not until the mid-1980s that retrospective safety data were collected and the safety issues of allergen immunotherapy addressed. In the United Kingdom, the Committee on Safety of Medicines (CSM) reported on 26 deaths associated with immunotherapy in the preceding 29 years [4]. A similar study by Lockey et al. [5] in the United States reported on 46 deaths over a 40-year period. The responses of the respective country's advisory bodies to these retrospective data collection series differed considerably. The UK CSM suggested that immunotherapy should only be carried out where full cardiopulmonary resuscitation facilities were immediately available and that patients should be kept under observation for a minimum of 2 h. The practice in the United States also altered following these observations with greater consideration of the risk factors identified through these reports and a minimum waiting time of 20 min requested [6]. The European Academy of Allergology and Clinical Immunology reviewed the available evidence and reached a consensus for a 30-min waiting period after injections [7]. A paper by Moreno et al. [8] in this issue extends these observations and recommendations of the safety of immunotherapy through a prospective multi-centre study of subcutaneous allergen immunotherapy of adults and children with rhinitis and/or asthma. This paper examined the prevalence of systemic side-effects, graded according to the EAACI immunotherapy position paper criteria, in 488 patients over 2 years. This study reports on over 17 000 injections through up-dosing and maintenance phases. The key figures from this extensive review are the number of individuals who experienced a systemic reaction (SR) (3.7%) and the number of SR per administered dose (0.3%∼1 in 333 injections). Interestingly, of the 18 individuals who experienced an SR, 11 experienced only a single SR throughout their course of therapy, with seven of these occurring in the up-dosing period. Two individuals experienced two or three SRs, with the remaining five patients experiencing 40% of all SRs. No grade IV SRs were noted and adrenaline was given on only seven occasions, each time for a grade 3 reaction. A number of other interesting observations are made within the paper. Firstly, the rate of SRs was not greater during the up-dosing phase compared with maintenance. It would be interesting to know the details of the maintenance phase reactions, in particular their time relationship to the end of up-dosing, and whether any alterations in medication had occurred (i.e. antihistamines/inhaled steroid usage). Previous studies have suggested that the use of prophylactic antihistamines before immunotherapy injections can reduce adverse reactions without impairing the effectiveness of immunotherapy [9, 10]. Previous studies have commented upon the higher SR frequency in those individuals with asthma and in those receiving mite immunotherapy compared with other allergy [11]. The inherent bias within such an association is the confounder that asthmatics more frequently receive mite immunotherapy. It would be interesting to sub-analyse the rhinitic and rhinitic +/− asthmatic cohorts for mite sensitivity to see if the SRs are significantly higher in the mite patients with rhinitis alone compared with the rhinitic pollen patients. Of those who experienced more than three SR, all were aged 15 years or less, male and had both rhinitis and asthma. Indeed, within this study, SRs are strongly associated with male sex (P=0.0001×10−3). Previous studies published in this journal have also found a lower risk of SR in those with only rhinitis and observed a risk of SR in those under the age of 20 compared with those >40 years of age [12]. There are currently no strict guidelines addressing the withdrawal of allergen immunotherapy after adverse reactions. Generally speaking, this is a clinical decision, which has to be based upon the type and severity of the SR, the context of the indication for immunotherapy, and the wishes of the patient. Of the six individuals with >three SRs within Moreno's study, half withdrew and half continued on a reduced dose. As the optimum dose for successful immunotherapy is not clearly established (although for most allergens it is thought to be >5 μg of allergen), the aims should be to use the minimum effective dose in all individuals who experience SRs. Alternatively, one could argue that exclusion of 1.2% (6/488) of individuals (of which half would withdraw anyway) from immunotherapy would reduce the SR from approximately 1 in 300 to 1 in 500 per injection. Finally, to set this all in perspective, we should note that a side-effect risk of 0.2% without any episodes of anaphylaxis (Grade IV) in over 17 000 injections compares favourably with the risk of anaphylaxis secondary to the administration of other medical treatments such as antibiotics and analgesics (1 in 10 000 exposed patients) [13]. A. P. Williams, M. T. Krishna and A. J. FrewMedical Specialties Clinical Group, Southampton General Hospital, Southampton SO16 6YD, UK E-mail: [email protected]
Abstract The aim of our study was to assess the utility of next generation sequencing (NGS) for predicting toxicity and clinical response to thiopurine drugs in paediatric patients with inflammatory bowel disease. Exome data for 100 patients were assessed against biochemically measured TPMT enzyme activity, clinical response and adverse effects. The TPMT gene and a panel of 15 other genes implicated in thiopurine toxicity were analysed using a gene based statistical test (SKAT-O test). Nine patients out of 100 (Crohn’s disease- 67, ulcerative colitis- 23 and IBDU-10) had known TPMT mutations associated with deficient enzyme activity. A novel and a highly pathogenic TPMT variant not detectable through standard genotyping, was identified through NGS in an individual intolerant to thiopurines. Of the 14 patients intolerant to thiopurines, NGS identified deleterious TPMT variants in 5 individuals whereas the biochemical test identified 8 individuals as intolerant (sensitivity 35.7% and 57.14%; specificity 93.75% and 50% respectively). SKAT-O test identified a significant association between MOCOS gene and TPMT activity (p = 0.0015), not previously reported. Although NGS has the ability to detect rare or novel variants not otherwise identified through standard genotyping, it demonstrates no clear advantage over the biochemical test in predicting toxicity in our modest cohort.
Primary immunodeficiencies (PIDs) are rare monogenic inborn errors of immunity that result in impairment of functions of the human immune system. PIDs have a broad phenotype with increased morbidity and mortality, and treatment choices are often complex. With increased accessibility of next-generation sequencing (NGS), the rate of discovery of genetic causes for PID has increased exponentially. Identification of an underlying monogenic diagnosis provides important clinical benefits for patients with the potential to alter treatments, facilitate genetic counselling, and pre-implantation diagnostics. We investigated a NGS PID panel of 242 genes within clinical care across a range of PID phenotypes. We also evaluated Phenomizer to predict causal genes from human phenotype ontology (HPO) terms. Twenty-seven participants were recruited, and a total of 15 reportable variants were identified in 48% (13/27) of the participants. The panel results had implications for treatment in 37% (10/27) of participants. Phenomizer identified the genes harbouring variants from HPO terms in 33% (9/27) of participants. This study shows the clinical efficacy that genetic testing has in the care of PID. However, it also highlights some of the disadvantages of gene panels in the rapidly moving field of PID genomics and current challenges in HPO term assignment for PID.
The impact of immunosuppression on interferon-γ release assays and novel cytokine biomarkers of TB infection, mycobacteria-specific IL-2, IP-10 and TNF-α responses was investigated in an ex vivo model. Cytokine responses in standard QuantiFERON-TB Gold in-Tube (QFT-GIT) assays were compared with duplicate assays containing dexamethasone or infliximab. Dexamethasone converted QFT-GIT results from positive to negative in 30% of participants. Antigen-stimulated interferon-γ, IL-2 and TNF-α responses were markedly reduced, but IP-10 responses were preserved. Infliximab caused QFT-GIT result conversion in up to 30% of participants and substantial reductions in all cytokine responses. Therefore, corticosteroids and anti-TNF-α agents significantly impair interferon-γ release assay performance. IP-10 may be a more robust TB biomarker than interferon-γ in patients receiving corticosteroids.
The current classification of inflammatory bowel disease (IBD) is based on clinical phenotypes, which is blind to the molecular basis of the disease. The aim of this study was to stratify a treatment-naïve paediatric IBD cohort through specific innate immunity pathway profiling and application of unsupervised machine learning (UML).In order to test the molecular integrity of biological pathways implicated in IBD, innate immune responses were assessed at diagnosis in 22 paediatric patients and 10 age-matched controls. Peripheral blood mononuclear cells (PBMCs) were selectively stimulated for assessing the functionality of upstream activation receptors including NOD2, toll-like receptor (TLR) 1-2 and TLR4, and the downstream cytokine responses (IL-10, IL-1β, IL-6, and TNF-α) using multiplex assays. Cytokine data generated were subjected to hierarchical clustering to assess for patient stratification.Combined immune responses in patients across 12 effector responses were significantly reduced compared with controls (P = 0.003) and driven primarily by "hypofunctional" TLR responses (P values 0.045, 0.010, and 0.018 for TLR4-mediated IL-10, IL-1β, and TNF-α, respectively; 0.018 and 0.015 for TLR1-2 -mediated IL-10 and IL-1β). Hierarchical clustering generated 3 distinct clusters of patients and a fourth group of "unclustered" individuals. No relationship was observed between the observed immune clusters and the clinical disease phenotype.Although a clinically useful outcome was not observed through hierarchical clustering, our study provides a rationale for using an UML approach to stratify patients. The study also highlights the predominance of hypo-inflammatory innate immune responses as a key mechanism in the pathogenesis of IBD.
'%3e%3cpath fill='%23012169' d='M0 0v30h60V0z'/%3e%3cpath stroke='%23fff' stroke-width='6' d='m0 0 60 30m0-30L0 30'/%3e%3cpath stroke='%23C8102E' stroke-width='4' d='m0 0 60 30m0-30L0 30' clip-path='url(%23b)'/%3e%3cpath stroke='%23fff' stroke-width='10' d='M30 0v30M0 15h60'/%3e%3cpath stroke='%23C8102E' stroke-width='6' d='M30 0v30M0 15h60'/%3e%3c/g%3e%3c/svg%3e)
