Mediator studies in skin blister fluid from patients with dual skin reactions after intradermal allergen injection

Skin blister fluid (SBF) samples obtained after allergen skin testing in a total of 26 patients with late cutaneous reactions (LCRs) were examined for the presence of various vasoactive mediators. Histamine was predominant during the early phase of the wheat and flare reaction (206 ± 40 ng/ml) and decreased with the development of the LCR toward normal SBF levels (around 20 ng/ml). Kallikrein activity was measurable in low amounts (around 5 ng/ml) in three out of 13 SBF samples taken 30 min after skin testing and in five of 13 SBF samples taken 6 hr after allergen testing. The thromboxane B₂ content of SBF showed an increase with the development of LCR (control skin 976 ± 483 ng/ml; allergen-tested skin 30 min after allergen injection, 1465 ± 1566 ng/ml; allergen-tested skin 6 hr after antigen injection, 1775 ± 731 ng/ml). SBF obtained from normal skin as well as from allergen-tested skin showed significant platelet-activating property as measured in an in vitro serotonin-release assay from washed human platelets. It is concluded that during the development of late-phase reactions a complex interaction of various mediator systems takes place.