Distribution of core fragments from the major cat allergen Fel d 1 is maintained among the main anatomical sites of production.
BACKGROUND
Polymorphism of Fel d 1 has long been observed, but structural characterization of Fel d 1 variants among the various sites of production and animals is still missing. This study was aimed at elucidating the structural polymorphism of this protein as a function of the site of production and the resulting influence on the immunological behavior of the allergen.


METHODS
Fel d 1 was water-extracted from the 4 main sites of production, i.e. cheek zone, interdigital zone, anal sac (AS), and chest area and a panel of 10 cats. Fel d 1-like materials were immunoblotted, immunopurified and characterized by MALDI-TOF MS. Immunoreactivity was studied using ELISA dose-dependent curves at equilibrium.


RESULTS
In all areas, 4-10 isoforms ranging from 7 to 40 kDa were detected by MS. Essentially two truncated heterodimers of 13-14 and 16-17 kDa were identified together with intact Fel d 1 in all compartments and they were largely predominant in AS. These core fragments were found to contribute to a variable recognition by antibodies in a panel of ELISA.


CONCLUSIONS
Our study identified truncated dimers of Fel d 1, probably resulting from proteolytic degradation of both chains and present in all cats. Core fragments are largely distributed among anatomical sites of production and especially well represented in AS. They are recognized as intact allergens by antibodies and may therefore introduce discrepancies in allergen measurement depending on the variable amount of intact and degraded Fel d 1 produced by the cat.
Bienboire-Frosini
Cécile
C
Phérosynthèse Research Institute, Le Rieu-Neuf, St-Saturnin d'Apt, France. c.frosini@pherosynthese.com
Lebrun
Régine
R
Vervloet
Daniel
D
Pageat
Patrick
P
Ronin
Catherine
C
D000485:Allergens / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry / Q000276:immunology; D000825:Animal Structures / Q000737:chemistry* / Q000276:immunology; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000937:Antigen-Antibody Reactions; D015153:Blotting, Western; D002415:Cats; D004797:Enzyme-Linked Immunosorbent Assay; D006023:Glycoproteins / Q000032:analysis* / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology; D008970:Molecular Weight; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000032:analysis* / Q000737:chemistry / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
D000485:Allergens; D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D010446:Peptide Fragments; C059296:Fel d 1 protein, Felis domesticus