Jadranka Živčić

Cut-off values for total serum immunoglobulin E between non-atopic and atopic children in north-west Croatia

Abstract Background: The aim of this study was to determine cut-off values for total serum immunoglobulin E (IgE) between non-atopic and atopic children with respiratory symptoms. Children of 0–16years of age were evaluated for respiratory symptoms of >4-week duration. Methods: Children were divided into two groups: non-atopic children (n=3355) who were non-IgE-sensitized with undetectable allergen-specific IgE (<0.35kIUA/L), and atopic children (n=4620) who were sensitized to ≥1 allergens (specific IgE ≥0.35 kIUA/L). Upper and lower centiles were determined and cut-off values calculated using receiver operating characteristic (ROC) analysis. Results: Serum total IgE increased with age in both groups, although at a variable level and rate, and reached a plateau at 9 and 10years in non-atopic and atopic children, respectively. Atopic children had on average 14-fold higher serum total IgE compared to non-atopic children. In both groups, the median was lower than the corresponding mean and the distribution skewness was always positive (group I, 0.87; group II, 0.91). In almost all age groups, the 95th percentile for non-atopic children corresponded to the calculated cut-off values, whereas the 10th percentile for atopic children corresponded to the respective cut-off values only until the age of 8years, after which greater differences between the cut-off values and the 10th percentile were recorded. Cut-off values for total serum IgE in children up to 16years were determined with diagnostic sensitivity, specificity and area under the ROC curve of 96%, 91% and 0.950, respectively. Conclusions: The 95th percentile for total IgE in non-atopic children and the 10th percentile in atopic children could be taken as cut-off values in children up to 8years of age, after which significant percentile discrepancies between non-atopic and atopic children were recorded. Since atopic subjects show a more irregular centile distribution, cut-off values are best determined by ROC analysis.

Eosinophil Cationic Protein in Children With Respiratory Allergies - When Is It Useful?

Background: To assess the differences in serum eosinophilic cationic protein (ECP) concentrations between treated and untreated children with asthma, children with rhinitis, and children with both and possible influence of seasonal exposure to sensitizing allergens on ECP levels. Methods: The study included treated (n=156) and untreated (n=55) children with asthma, children with rhinitis, and children with asthma and rhinitis. Serum ECP was measured in serum collected between 8 am and 12 pm under standardized pre-analytical conditions (regarding the type of blood collection tube, time, and incubation temperature during blood clotting). Results: Untreated children had significantly higher ( P <0.0001) concentrations of ECP (M[IQR]=35.1 [29.5–50.9] μg/L) than treated children (M[IQR]=11.3 [7.1–16.1] μg/L). Eosinophilic cationic protein was significantly higher during the allergen exposure season (M[IQR]=23.9 [17.6–40] μg/L) than out of season (M[IQR]=8.3 [5.4–17.2]) μg/L, P =0.0001. Conclusions: To make ECP measurements useful in clinical practices, it is necessary to meet standardized pre-analytical conditions. * ECP : eosinophilic cationic protein IL-2 : interleukin-2 ARIA : Allergic Rhinitis and its Impact on Asthma GINA : Global Initiative for Asthma IgE : immunoglobulin E FeNO : fraction of exhaled nitric oxide

Allergen Specific Immunoglobulin E in Children Under 6 Years Old With Total Immunoglobulin E Below 10 kU/L

Laboratory diagnosis of type I hypersensitivity reaction is based on the determination of serum concentrations of total immunoglobulin E (tIgE) and allergen specific IgE (sIgE) antibodies. Serum concentration of tIgE varies throughout the lifespan. 1 Physiologic changes are mainly noticeable in the first decade of life. In spite of defined reference intervals for tIgE, as many as 5% of healthy children might have serum tIgE concentrations above the age-specific reference range, whereas 10% of children with clinical signs of hypersensitivity might have serum tIgE concentrations within the age-specific reference range. 1 As the concentration of circulating IgE antibodies might not always correlate with local tissue IgE synthesis, screening of sensitized individuals based on serum tIgE concentrations may prove inadequately reliable in some cases. 2 An increased concentration of sIgE indicates sensitization to a particular allergen. In sensitized individuals, only 5% of total sIgE production is found in the circulation, indicating current immune activity, whereas the rest of the sIgE is bound to tissue mastocytes and mediates local bioactivity. 3

Increased IgA in a subject with positive anti-thyroid autoantibodies – a case report

Introduction: Increased concentrations of antithyroid autoantibodies are found in inflammatory diseases as well as in thyroid autoimmune disorders. The aim of this report is to present increased IgA concentrations in a female patient with positive anti-thyroid autoantibodies. Results throughout 13 months of follow-up are presented. Materials and methods: The levels of thyroid hormones and antibodies in the serum samples were measured using microparticle enzyme-immunoassay. IgA was determined by two immunochemical methods, immuno-turbidimetric method and radial immunodiffusion, respectively. Results: Initial thyroid function tests showed normal values of T3, T4 and thyroid stimulating hormone (TSH), and increased values of thyroid peroxidase autoantibodies (anti-TPO), anti-thyroglobulin (anti-Tg) autoantibodies and IgA. The patient underwent treatment with single daily dose of levothyroxine. The elevated initial levels of anti-TPO stabilized with the administration of levothyroxine, while anti-Tg remained increased. IgA determined by immuno-turbidimetric method was significantly increased during the follow-up period. Repeated determination of IgA by radial immunodiffusion revealed lower IgA concentrations. Conclusion: Possible false increased IgA values could be a result of both, interferences of goat anti-IgA antibodies from reagents, and cross-reactivity with endogenous anti-Tg autoantibodies in serum, respectively. Further investigations are needed to ascertain the cause of increased IgA values in patient with positive anti-thyroid autoantibodies.