Miljenko Raos

Interferon-γ release assay for the diagnosis of latent tuberculosis in children younger than 5 years of age.

Background: There are limited data available on interferon-&ggr; release assay (IGRA) performance in children up to 5 years of age, with documented exposure to active tuberculosis (TB). The aim of this study was to evaluate (1) the influence of infectivity of adult source cases on test results, (2) the impact of age, and (3) the level of agreement, between IGRA and tuberculin skin test (TST) results. Methods: A total of 142 Bacille Calmette-Guerin-vaccinated children up to 5 years of age were investigated because of a history of exposure to active TB. QuantiFERON-TB Gold In-Tube IGRA (QFT) and TST assays were performed. Results: Test results were significantly influenced by positive finding of cavitary lesions (QFT, odds ratio [OR] = 6.15; TST, OR = 7.48) and positive acid-fast bacilli (QFT, OR = 4.01; TST, OR = 4.47) in active TB contacts. QFT resulted in 1 indeterminate response (0.7%), attributable to low mitogen. There was no evidence for age having any effect on QFT performance. The 2 tests showed a moderate overall concordance (89%; &kgr; = 0.591) at a TST cutoff value of ≥10 mm. Conclusions: Association of positive QFT and TST results with risk factors for infection in child contacts (presence of cavitary lesions and acid-fast bacilli smear positivity in index cases) suggests that both the tests have good diagnostic accuracy. However, there was significant discord between results of the 2 tests that could not be definitively resolved. Thus, in a high-risk population of children up to 5 years of age, both tests (QFT and TST) should be performed and the child should be considered infected if either or both tests are positive.

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.

Bisalbuminemia in Two Croatian Families

BACKGROUND Bisalbuminemia is a dysproteinemia characterized by the occurrence of two albumin fractions on serum protein separation by electrophoresis on cellulose acetate sheets. Bisalbuminemia may occur as a hereditary trait or as analytical interference with some drugs, especially penicillin. METHODS Two patients with the finding of bisalbuminemia are presented. Both patients (patient 1 was a 4-1/2-month-old male infant, and patient 2 was a 15-year-old boy) were admitted for respiratory infection. RESULTS Bisalbuminemia was detected by serum protein electrophoresis and confirmed by isoelectric focusing in pH gradient gel (pH range 4.0-6.5). This finding was supported by simultaneous detection of abnormal albumin in the mother of patient 1, while the father had normal albumin. The abnormal fast albumin in both patients had an increased relative mobility of 1.08 when measured from the sample application position. CONCLUSIONS The results presented are the first description of albumin mutations in Croatia (that according to the CISMEL group could be classified as ZC/HZ), and present the first step in identification prior to determination of structural change and amino acid sequence in the albumin molecule.

Alkaline phosphatase isoenzymes in children with respiratory disease

Aim: To present the electrophoretic pattern of alkaline phosphatase (ALP) isoenzymes in serum of infants and children exhibiting increased total ALP catalytic activity in the course of acute respiratory disease. Subjects and methods: Results obtained in 21 children (17 of them infants), including 13 male and eight female children aged 2 months to 8 years, hospitalized for respiratory diseases are presented. Total ALP catalytic activity was determined and electrophoretic separation of ALP isoenzymes was performed in childrens sera. Results: Increased total ALP catalytic activity (range, 528-5622 U/L) during hospital stay was recorded in eight (38.1%) children. A typical picture of be-nign transient hyperphosphatasemia (TH), which implies the occurrence of fast anodal fraction (faster than hepatic fraction) and near-cathode fraction (faster than bone fraction), was recorded in five children. The placental-like isoenzyme was detected in two children. Expression of bone fraction and placental-like fraction was recorded in a rachitic child. Prehepatic ALP was expressed in two children, and hepatic ALP isoenzyme in one child. Conclusion: Acute respiratory disease in infants and children may entail transient increase in the ALP catalytic activity with the occurrence of various isoenzyme bands such as fast anodal and near-cathode fraction (in TH), prehepatic fraction and placental-like fraction. TH is verified when total ALP activity has decreased and returned to reference intervals. In this case, no additional testing is required.

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

Interferon Gamma Release Assay in a 12-month-old BCG-Vaccinated Infant with Latent Tuberculosis Infection and Isolated Mycobacterium fortuitum

The aim is to present a case of serial use of interferon-γ release assay (IGRA) test in the evaluation of an infant with a latent tuberculosis infection (LTBI) accompanied with a positive finding of Mycobacterium (M.) fortuitum in gastric juice. In addition to routine diagnostic evaluation (tuberculin skin test (TST), culture of gastric juice, chest X-rays), a 12-month-old female infant with a history of close family contact and a case of active tuberculosis was investigated with IGRA (QuantiFERON-TB Gold In-Tube, Cellestis, Carnegie, Australia). Tuberculin skin tests were positive. The first result of IGRA (on admission) was negative; the second (day 16) and third (day 57) results of IGRA were positive. M. fortuitum was cultured from gastric juice samples. Positive IGRA finding confirmed LTBI, and prophylaxis with isoniazid was administered. Since M. fortuitum does not express antigens that could be confirmed by the QuantiFERON-TB Gold In-Tube test, isolation of M. fortuitum could be interpreted as a possible contamination.