Low indoleamine 2,3-dioxygenase activity in persistent food allergy in children.

BACKGROUND: Indoleamine 2,3-dioxygenase (IDO), which degrades tryptophan (Trp) to kynurenine (Kyn), has been demonstrated to contribute to modulation of allergic responses. However, the role of IDO in food allergy has not yet been elucidated. METHODS: Serum Trp and Kyn concentrations were analyzed by high-pressure liquid chromatography. Expression of IDO gene was measured by real-time PCR. The levels of interleukin (IL)-4, IL-10, and interferon (IFN)-γ in cell culture supernatants were measured by ELISA. RESULTS: Kyn/Trp (IDO activity) was significantly lower in subjects with food allergy (n = 100) than in aged-matched healthy controls (n = 112) (P = 0.004). Kyn/Trp was decreased from healthy through completely tolerant, partially tolerant, and reactive ones [LN transformation (mean ± SEM) healthy: 3.9 ± 0.02 µM/mM; completely tolerant: 3.83 ± 0.04; partially tolerant: 3.8 ± 0.06; reactive: 3.7 ± 0.04] (P = 0.008). The frequency of genetic polymorphisms of IDO did not reveal a significant association with Trp, Kyn, and Kyn/Trp in healthy and food-allergic cases. Culture of PBMC experiments yielded that IDO mRNA expression was not different between tolerant and reactive groups. IL-4 synthesis when stimulated with casein increased significantly in subjects who are reactive and tolerant to foods (P = 0.042, P = 0.006, respectively). Increase in IL-10 synthesis was observed only in children tolerant to milk, but not in reactive ones. IFN-γ synthesis, when stimulated with IL-2 and ß-lactoglobulin in cell culture, was significantly higher in subjects tolerant to milk than in the reactive ones (P = 0.005 and P = 0.029, respectively). CONCLUSION: Our results imply the probability of involvement of IDO in development of tolerance process, and we presume that high IDO activity is associated with nonresponsiveness to food allergens despite allergen sensitization.

Importance of serum basal tryptase levels in children with insect venom allergy.

BACKGROUND: The importance of serum basal tryptase (sBT) levels on patients with venom allergy is highlighted in recent adulthood studies. The aim of this study was to evaluate the sBT levels of venom-allergic children with varying severity of clinical reactions. We also aimed to document the association between sBT levels and severe systemic reactions (SR). METHODS: Serum basal tryptase levels were estimated by UniCAP (Pharmacia & Upjohn, Uppsala, Sweden). Children who suffered from large local reaction (LLR) or SR after insect stings were included along with healthy control subjects without a history of any local or SR after insect stings. RESULTS: A total of 128 children (55 with SR, 18 with LLR, and 55 age and sex-matched control subjects) with a median age of 8.9 years (range 3.2-17.4) were enrolled. Severe SR was encountered in 24 (44%) patients with SRs. The median level of sBT in children with SRs (median, interquartile range) [4.2 µg/l (3.6-4.9)] was significantly higher than in children with LLRs [3.1 µg/l (2.5-4.0)] and healthy control subjects [2.9 µg/l (2.3-3.4)] (P < 0.001). Logistic regression analysis revealed sBT ≥ 4.8 µg/l as a significant risk factor for severe SR (5.7 [1.5-21.4]; P = 0.01) in children with venom allergy. CONCLUSIONS: Our results indicate that sBT levels are associated with a higher risk of severe SR in children with insect venom hypersensitivity. Determination of sBT levels may help clinicians to identify patients under risk of severe SRs and optimal and timely use of therapeutic interventions in children with venom allergy.

Erythrocyte zinc levels in children with bronchial asthma.

Zinc deficiency may be suspected to play a role in the pathogenesis, control, and severity of asthma because of its antioxidant, antiapoptotic, and anti-inflammatory effects. We aimed to investigate whether there was any relationship between erythrocyte zinc levels and childhood asthma. The erythrocyte zinc levels of 67 asthmatic and 45 healthy children were analyzed in this case-control study. The mean concentrations of erythrocyte zinc were 1215.8 ± 145.1 µg/dl in asthma patients and 1206.9 ± 119.5 µg/dl in controls with no significant difference (P = 0.472). The erythrocyte zinc level was below 1,000 µg/dl in 6 asthmatic patients (8.9%) and 2 control group patients (4.4%). There was no relationship between erythrocyte zinc levels and duration of follow-up, severity, and control of the asthma (P > 0.05). On the other hand, patients hospitalized for an asthma attack had significantly lower erythrocyte zinc levels compared with nonhospitalized patients and the control group (P = 0.000 and P = 0.004 respectively). This study's findings indicate that asthmatic children are not a risk group for zinc deficiency. We emphasize that checking zinc levels in children who are hospitalized for an asthma attack may be useful.