Analysis of rat urine proteins and allergens by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting

Abstract

Background: In rats, urine has been identified as a major source of the allergens that cause laboratory animal allergy an important occupational health problem. Methods and Results: Urinary proteins and allergens of Wistar rats were studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. Proteins excreted by male and female rats during puberty were similar and of low molecular weight. In adulthood, moderate increases in diffuse staining of 26 and 21 kd occurred in female urine. In males the 17 kd protein increased dramatically and the 23 and 21 kd proteins moderately. The urine excretion of high-molecular-weight proteins (75 to 63 kd) increased with age in males (females not studied). Immunoblot studies with six sera showed allergens in urine of male and female rats of all ages, three of which were present in all urine (75, 68, and 21 kd). Three allergens (17, 16, and 15 kd) in female urine may be allergenically similar to the 17 kd allergen in adult male urine. Adult male urine allergens were studied further with sera from 83 rat-hypersensitive subjects. Major allergens were identified at 23, 21, and 17 kd, and all sera had IgE to one or more of these proteins. Twenty-seven percent had IgE to 68 and 63 kd allergens. Minor allergens were identified at 75, 51, and 44 kd. Conclusions: Rat urine is an important source of the major allergens associated with rat hypersensitivity. Age and sex markedly influence the protein and allergenic constituents of rat urine.