Comparison of weal and flare responses to platelet activating factor (PAF) and histamine, and the ultrastructural effects of PAF in the skin of atopic and normal subjects

Weal volume and flare area responses to intradermal platelet activating factor (PAF) and histamine, both in the presence and absence of the protein carrier, human serum albumin (HSA), were measured in the skin of normal subjects, atopics without dermatitis, and in the normal‐appearing skin of patients with atopic dermatitis. The ultrastructural effects of intradermal PAF were also studied in the same groups of subjects. Weal and flare dose–responses to PAF were enhanced by the presence of human serum albumin, HSA itself producing a significantly greater mean weal response in each group than lyso‐PAF (P