Allergenicity of the cat flea (Ctenocephalides felis felis)

Summary Adult fleas, spent and unspent culture media were extracted and the radio‐atlergosor‐bent test (RAST) performed with sera of 48 cat flea skin test‐positive individuals from the Tampa Bay area of Florida. Sixteen sera (33.6%) had a positive RAST to the cat flea extract prepared in our laboratory [1.7‐11.4% of the total counts (TC) added]. Six of the 16 sera (12.5%) also contained specific IgE to allergens in thespent medium (0.8‐3.3% TC). The allergen composition and strength were studied by RAST inhibition of two commercial cat flea extracts and compared with our in‐house flea extract. The results demonstrated similar allergen compositions and different potencies. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) of the in‐house flea extract showed several Coomassie blue‐stained bands (10–85 kD). SDS‐PAGE immunoblols revealed five IgE‐binding bands at 34, 35, 39, 54 and 60 kD. Flea allergens were quantified in eight house dust samples using RAST inhibition assays and expressed as RAST inhibition units; five of these samples contained detectable levels. Cat flea allergens may contribute to the allergenicity of house dust in areas of heavy llea infestation.