Diagnostic Value of Serum Specific IgE to Toxocara canis in Patients with Eosinophilia

Abstract

Background: Toxocariasis is one of the major causes of peripheral eosinophilia and it provokes eosinophilic infiltration in the internal organs. Diagnosis of toxocariasis has relied mainly on the immunological methods including measurement of serum specific IgG to Toxocara canis excretory-secretory antigen (TES-Ag) in which the detection rate by ELISA was 68% in patients with eosinophilia. Objective: The aim of this study is to measure serum specific antibodies to TES-Ag in patients with peripheral eosinophilia in order to evaluate the clinical significance. Method: Twenty-one patients with peripheral eosinohilia (＞500 cells/uL or ＞10% of total white blood cell count), who have no identifiable cause of eosinophilia such as drugs, well known parasite infection, malignancy or allergic diseases, were enrolled. Serum specific IgE, IgG1 and IgG4 antibodies to TES-Ag were determined by ELISA (Phadia, Uppsala, Sweden) which were compared to those of specific IgE by immunoCAP system (Phadia), and specific IgG to TES-Ag by ELISA (Bordier). Serum total IgE and ECP levels were measured by immunoCAP system. Result: The detection rate of serum specific IgE by ELISA was the highest (90.5%) followed by serum specific IgG1 (65%) and IgG4 (75%). Concordance rate of specific IgE by ELISA and immunoCAP was 100%, while that between specific IgE by ELISA (home-made) and specific IgG by ELISA (Bordier) was 60%. The most commonly involved organ was liver (57.1%). Serum total IgE level in patients with liver involvement was significantly higher than those without it (P＜0.01). onclusion: Toxocariasis should be considered as one of the major causes of the patients with eosinophilia in this country. Measurement of serum specific IgE to TES-Ag may be useful to evaluate the Toxocara canis infection.