The role of basophils in the immunopathogenesis of hypersensitivity to fleas (Ctenocephalides felis) in dogs.

Biopsies taken of skin test sites from 10 dogs allergic to fleas were fixed in Karnovsky's fixative and embedded in methacrylate. One micron sections were stained with acid Giemsa for identification of basophils. This cell was identified in most biopsies taken at intervals from 1 hour to 48 hours post-injection. The proportion was highest between 4 hours and 18 hours and had substantially fallen by 48 hours. The highest number of basophils recorded as a percentage of the inflammatory infiltrate was 22.1%, with biopsies from 7 of the 10 dogs showing in excess of 10% basophils at some point. The results suggest that cutaneous basophil hypersensitivity may play an immunopathogenic role in flea-bite hypersensitivity in dogs.