The Lights and the Shadows of Controlled Sting Challenge With Hymenoptera.

Hymenoptera venom immunotherapy (VIT) is effective for protecting individuals with systemic allergic reactions caused by Hymenoptera stings. The need for a tool that shows the degree of protection afforded by VIT and the lack of useful biomarkers have made the sting challenge test (SCT) the gold standard for this disorder, although its use has both lights and shadows. SCT with Hymenoptera involves causing a real sting in a patient diagnosed with allergy to the venom of the stinging insect and who is undergoing treatment with specific immunotherapy. In Spain, SCT is included in the list of services offered by some hospitals and forms part of their daily clinical practice. This review aims to analyze the strengths and weaknesses of this test and to describe the standardized procedure and necessary resources, based on the experience of a group of Spanish experts and a review of the literature.

Variability of the L-Histidine decarboxylase gene in allergic rhinitis.

BACKGROUND: Nonsynonymous polymorphisms in genes coding for histamine-metabolizing enzymes, diamine oxidase and histamine N-methyltransferase are related to the risk of developing allergic diseases. The role of polymorphisms in the histidine decarboxylase gene remains unexplored. The objective of this study is to identify novel polymorphisms in the human histidine decarboxylase gene and to analyse the clinical association of nonsynonymous polymorphisms with rhinitis. METHODS: We performed a single-strand conformational polymorphism analysis of the histidine decarboxylase gene sequence. The presence of two nonsynonymous polymorphisms Thr31Met (rs17740607) and Glu644Asp (rs2073440) was analysed in 442 unrelated patients with allergic rhinitis, 233 of whom also had asthma, and in 486 healthy subjects. RESULTS: We observed three novel polymorphisms designated as ss50402829, ss50402830 and ss50402831-(rs17740607) with allele frequencies = 0.005, 0.208 and 0.073, respectively. Statistically significant differences were observed for the histidine decarboxylase Glu644Asp (rs2073440) polymorphism, with OR (95% CI) values for homozygous carriers of the Glu644 allele equal to 3.12 (1.75-5.56, P < 0.00005) for all patients, 3.38 (1.54-7.44, P = 0.002) for patients with rhinitis alone, and 2.92 (1.43-5.95), P = 0.003 for patients with rhinitis + asthma, when compared with healthy controls. A significant Glu644 gene-dose effect was observed for overall patients (P = 0.0001), for patients with rhinitis alone (P = 0.005) and for patients with rhinitis + asthma (P = 0.010). CONCLUSIONS: The HDC allele Glu644 in homozygosity increases the risk of developing rhinitis in the studied population. This adds to increasing evidence supporting a prominent role of genetic variations related to histamine homeostasis in the risk to develop allergic diseases.