Abstract
BackgroundFurry animals are an important source of indoor allergens. Diagnosis of allergy to small pets such as guinea‐pigs still relies on animal dander extracts which do not allow to define the primary sensitization source.ObjectiveTo identify major guinea‐pig allergens and to evaluate their potential as marker allergens for in vitro IgE‐diagnosis in comparison with dander extracts.MethodsA group of patients allergic to guinea‐pig (n = 29) and a group of patients allergic to cat and dog (n = 30) were recruited for the study. A panel of four guinea‐pig lipocalin allergens was expressed as recombinant proteins in E. coli. Specific IgE were quantified by ImmunoCAP and ELISA.ResultsThe combination of 4 guinea‐pig lipocalin allergens, including 2 new lipocalins, Cav p 1.0201 and Cav p 6.0101, and the previously characterized lipocalins Cav p 2 and Cav p 3, enabled the identification of 90% of all patients allergic to guinea‐pig. The vast majority had specific IgE to Cav p 1 (83%). Cav p 6 shares 54% sequence identity with Fel d 4 and Can f 6 and was found to be IgE‐cross‐reactive with these allergens. In the group of cat‐ and dog‐allergic patients, 73% had also specific IgE to guinea‐pig dander. However, only 27% of the cat /dog‐allergic patients had specific IgE to any of the non‐cross‐reactive guinea‐pig allergens Cav p 1, Cav p 2 or Cav p 3. The high prevalence of IgE to guinea‐pig dander could be explained by IgE‐cross‐reactivity among serum albumins and certain lipocalins.Conclusions and clinical relevanceThe availability of specific allergen markers is essential for the assessment of primary sensitization, especially in polysensitized patients. The proposed panel of guinea‐pig allergens Cav p 1, Cav p 2 and Cav p 3 is a first step to component‐resolved IgE‐diagnosis of allergy to small furry pets.
Highlights
In western life-style countries, pet dander is a major cause of inhalant allergy and sensitization to furry animals is a major risk factor for developing allergic asthma and rhinitis. 1-3 Cats and dogs are the main allergen sources, but numerous small furry animals, kept nowadays as pets, gain more and more importance.[4,5] Among laboratory animal workers, occupational allergy to rabbits and rodents is highly prevalent.[6]
A reliable distinctive element is sensitization to a specific marker allergen such as the major cat allergen Fel d 1.9 On the contrary, sensitization to a member of the cross-reacting family of serum albumins, or to the Fel d 4/Can f 6/Equ c 1 lipocalin subgroup will often give positive results with several animal dander extracts and may be wrongly interpreted as true primary sensitization.10-12 For small furry pets, many allergens remain undefined and in vivo and in vitro diagnosis commonly relies on allergen extracts.[13]
IgE-binding to Fel d 4 and Can f 6 could only partially be inhibited by Cav p 6 (41% and 35%, respectively). This patient was initially diagnosed as guinea- pig sensitized, but it turned out that he was sensitized to several furry animals and that, according to the inhibition results with Cav p 6, his sensitization to guinea-pig is a cross-sensitization from cat and dog
Summary
In western life-style countries, pet dander is a major cause of inhalant allergy and sensitization to furry animals is a major risk factor for developing allergic asthma and rhinitis. 1-3 Cats and dogs are the main allergen sources, but numerous small furry animals, kept nowadays as pets, gain more and more importance.[4,5] Among laboratory animal workers, occupational allergy to rabbits and rodents is highly prevalent.[6]. The objective of the present study was to provide specific marker allergens for the diagnosis of allergic sensitization to guinea- pig, a pet with a high sensitizing power.[6] Four guinea-pig lipocalin allergens including 2 new recombinant allergens were assessed for their diagnostic value in a cohort of guinea-pig-allergic patients and used to analyse potential cross-reactivities in a cohort of allergic patients sensitized to both cat and dog. Two new lipocalins, named Cav p 1.0201 and Cav p 6.0101 by the WHO/IUIS allergen nomenclature subcommittee, were purified from guinea-pig hair by ion exchange chromatography. Cav p 4, guinea-pig serum albumin, was purchased from Sigma-Aldrich. Specific IgE (sIgE) to recombinant Cav p 1, Cav p 2, Cav p 3, Cav p 6 and to native Cav p 4 (serum albumin), as well as recombinant Fel d 4 and Can f 6, were measured by ELISA as described.[15]
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