Platelet-activating factor-induced immediate and late cutaneous reactions.

Area of Science:

• Dermatology
• Immunology
• Pharmacology

Background:

• Platelet-activating factor (PAF) is implicated in allergic skin reactions.
• Understanding PAF's role in atopic subjects and chronic urticaria is crucial for developing effective treatments.

Purpose of the Study:

• To investigate the effects of platelet-activating factor (PAF) on skin reactions in atopic subjects and patients with chronic urticaria.
• To evaluate the efficacy of cetirizine in blocking PAF-induced skin inflammation and eosinophil accumulation.

Main Methods:

• Intradermal injection of PAF in atopic subjects and chronic urticaria patients.
• Assessment of immediate edema and late cutaneous reactions (LCR).
• Skin window technique to quantify eosinophil accumulation at various time points.
• Administration of cetirizine (10 mg twice daily) to assess its inhibitory effects.

Main Results:

• PAF induced immediate edema and significant eosinophil accumulation in atopic subjects, both markedly blocked by cetirizine.
• In chronic urticaria patients, PAF triggered immediate and late cutaneous reactions, accompanied by degranulated eosinophil infiltration, which were also inhibited by cetirizine.
• Cetirizine demonstrated significant efficacy in inhibiting PAF-induced inflammatory responses in the skin.

Conclusions:

• Platelet-activating factor (PAF) plays a significant role in inducing immediate and late-phase skin reactions, including eosinophil infiltration, in atopic subjects and chronic urticaria patients.
• Cetirizine effectively blocks PAF-mediated inflammatory responses in the skin, suggesting its therapeutic potential in conditions involving PAF.
• The study highlights the pathophysiological mechanisms of PAF-induced skin reactions and cetirizine's mechanism of action.