RELEASE OF MONOCYTE CHEMOATTRACTANTS BY POLYMORPHONUCLEAR LEUKOCYTES STIMULATED BY THEIR ADHESION TO STRATUM-CORNEUM OPSONIZED VIA COMPLEMENT ACTIVATION, MEASURED WITH A HUMAN ACUTE MONOCYTIC LEUKEMIC-CELL LINE, THP-1

Stratum corneum (SC) exposed to living tissues, induces inflammation c haracterized by the formation of mixed cell granulomas consisting of i nfiltrative polymorphonuclear leukocytes (PMNs) and monocytes/macropha ges. In this study, to clarify the mechanism for the later monocyte ac cumulation in SC-induced granulomas, we evaluated monocyte chemotactic activity induced by PMNs treated with serum-opsonized SC by using a h uman acute monocytic leukemic cell line, THP-1. When the supernatant w as obtained from a PMN suspension cultured with opsonized plantar SC, higher THP-1 chemotactic activity was detected as compared with that c ultured with non-opsonized SC. Although some concentrations of the che mokines, MIP-1 alpha and MIP-1 beta, were detected in supernatants obt ained from the PMN suspensions cultured with plantar SC than in the co ntrol suspensions of PMN alone, their production by PMN was not influe nced by the opsonization procedure. In contrast, MCP-1 was found to be secreted from PMN suspensions constitutively, showing no correlation to this THP-1 chemotactic activity. Moreover, HPLC analysis of PMN sus pensions indicated that factors with far higher molecular weight value s than these chemokines are involved in the chemotaxis of THP-1 cells.