Evaluation of two new recombinant guinea-pig lipocalins, Cav p 2 and Cav p 3, in the diagnosis of guinea-pig allergy.
BACKGROUND: Guinea-pigs, classical laboratory animals now often kept as pets, regularly elicit important allergic reactions. Two guinea-pig allergens have been described previously to some extent; however, biomolecular and immunological data are lacking. OBJECTIVE: To identify major guinea-pig allergens, produce them as recombinant proteins and define their allergenic potential and clinical importance in allergic patients. METHODS: Protein extracts were prepared from various guinea-pig tissues and allergens were purified by ion exchange chromatography. The N-termini of two immunoglobulin E (IgE)-reactive proteins were determined and degenerate primers were designed for cDNA amplification by RT-PCR. Allergenic properties of recombinant proteins were assayed by immunoblotting, ELISA and mediator release assays. Specific IgE were quantified in the sera of 26 guinea-pig-allergic patients. RESULTS: Major IgE-reactive proteins were detected in submaxillary and harderian gland extracts. Two proteins were identified and the cDNAs were cloned. The 17 kDa protein expressed in the harderian gland corresponds to the previously described Cav p 2. The 19 kDa protein, Cav p 3, is a new allergen expressed in the submaxillary gland. Recombinant Cav p 2 and Cav p 3 were recognized by IgE antibodies from 65% and 54% of guinea-pig-allergic patients, respectively. Both proteins demonstrated equivalent allergenic activity in the mediator release assays. CONCLUSION AND CLINICAL RELEVANCE: Two major guinea-pig allergens, Cav p 2 and Cav p 3, have been characterized and produced as recombinant proteins. Combined to guinea-pig serum albumin, the new allergens proved to be valuable in the component-resolved diagnosis of guinea-pig allergy.