Total IgE level in respiratory allergy: study of patients at high risk for helminthic infection.

OBJECTIVE Eosinophilia and increased serum IgE levels are indicators of atopy; however, other factors can also play a key role, such as intestinal parasitic infections. This study assesses the relationship between total serum IgE, eosinophil count, and anti-Ascaris IgE in individuals with asthma and/or allergic rhinitis. METHODS A cross-sectional study was carried out in adolescents with asthma and/or allergic rhinitis. The patients had their total serum IgE, anti-Ascaris IgE and eosinophil count measured. RESULTS A total of 101 patients aged 12 to 21 years were assessed. Median IgE level was 660 IU/mL (P(25-75) 243.5-1500), and the eosinophil count corresponded to 510 cells/mm(3) (P(25-75) 284-811). Anti-Ascaris IgE was positive in 73% (74/101) of the individuals, but parasitological stool examination yielded positive results in only 33.7% (34/101). The correlation coefficients were the following: 0.34 (p = 0.001) between total IgE level and eosinophil count, 0.52 (p < 0.001) between total IgE level and anti-Ascaris IgE, and 0.26 (p = 0.01) between eosinophil count and anti-Ascaris IgE. The final multiple linear regression model pointed out that anti-Ascaris IgE contributed to a total serum IgE level with a coefficient of determination (adjusted R(2)) of 0.25 (F = 12.35; p < 0.001). This effect occurred regardless of eosinophil count and of the presence of intestinal helminthic infection. CONCLUSION In patients with respiratory allergy and increased total serum IgE levels living in areas where there is a high risk for helminthic infections, the quantification of anti-Ascaris IgE can be more useful and more insightful than the parasitological stool examination.