Anaphylaxis caused by the new ant, Pachycondyla chinensis: demonstration of specific IgE and IgE-binding components.

Abstract

BACKGROUND: There have been no reports dealing with the pathogenic mechanism and IgE-binding components in patients with anaphylaxis caused by a sting from Pachycondyla chinensis.

OBJECTIVES: This study was conducted to observe the clinical features of patients with P chinensis -induced anaphylaxis. The roles of specific (s) IgE and sIgG4 antibodies were evaluated, and IgE-binding components were identified.

METHODS: Seven patients with P chinensis -induced anaphylaxis and 15 unexposed control subjects were enrolled. P chinensis ants were collected at the patients' homes, and venom was prepared as P chinensis extract. Five patients complained of bee venom-induced anaphylaxis and had positive sIgE levels to yellow jacket venom, wasp venom, or both as well. Serum sIgE and sIgG4 were detected by means of ELISA. To identify IgE-binding components within P chinensis extracts, 12% SDS-PAGE with immunoblot analysis was applied.

RESULTS: All patients had positive skin prick test responses to P chinensis antigen and positive sIgE levels. Five (71%) patients had positive sIgG4 levels. Eight IgE-binding components (58, 46, 3l, 29, 27, 25, 22, and 12 kd) were noted, and the component at 12 kd was the most frequently found allergen (85%). IgE ELISA inhibition tests were performed on 2 groups of sera: one from patients with anaphylaxis induced by both P chinensis and bee venom (group A) and the other from patients with anaphylaxis induced by P chinensis venom alone without bee venom allergy (group B). ELISA inhibition tests with serum from group A showed significant inhibitions with addition of P chinensis extract, partial inhibitions with yellow jacket antigen, and minimal inhibitions with wasp or imported fire ant antigens. However, ELISA inhibition tests with serum from group B showed significant inhibitions with P chinensis antigen but no inhibition with wasp, yellow jacket, or imported fire ant antigens.

CONCLUSIONS: IgE-mediated reactions contributed to the development of P chinensis -induced anaphylaxis. Eight IgE-binding components and one major allergen (12 kd) were identified. Further studies will be needed to clarify the role of sIgG4 and to identify allergenic relationships with major bee and wasp allergens.