Figure 5

Histology of skin biopsies following intradermal challenge with HDM allergens. Histological staining of skin from (A) control and (B-D) HDM-sensitized sheep 48 h following cutaneous challenge with whole HDM extract shows extensive infiltration of eosinophils into the upper and lower dermal regions in skin of sensitized sheep (arrows); H&E stain (A, B), original magnification ×100. (C, D) Immunostaining for tryptase-positive mast cells in skin of sensitized sheep shows scattered mast cells (open arrowheads) together with eosinophils (arrowheads) throughout the dermis and in close proximity to blood vessels; Giemsa counterstain, original magnification ×200, ×1000).