Localization of IL-8 and Complement Components in Lesional Skin of Psoriasis vulgaris and Pustulosis palmaris et plantaris

BACKGROUND: Munro's microabscesses are a characteristic histopathologic feature of psoriasis vulgaris; however, the pathomechanisms underlying the migration of transepidermal leukocytes (PMNs) have not been fully elucidated yet. OBJECTIVE AND METHODS: Since the lesional scale extracts contain potent chemoattractants, such as IL-8 and C5a fragments, we studied their location in the lesions of psoriasis vulgaris and PPP with immunohistochemical techniques. RESULTS: Localization of IL-8 was not detected in the subcorneal keratinocytes but was demonstrated only in the basal keratinocytes together with migrating PMNs. In contrast, the presence of a complement fragment, C3b, was observed on the cell membranes of subcorneal keratinocytes, suggesting that these were the sites of complement activation. CONCLUSION: Such distinct localization of IL-8 and complement components suggests that the intraepidermal migration of PMNs takes place first according to the concentration gradient of IL-8, and thereafter they are guided by complement components to the final destination, the subcorneal portion of the lesional skin.