Thy-1 -positive dendritic epidermal cells contain a killer protein perforin

Abstract

The killer cell characteristics of Thy-1-positive dendritic epidermal cells (Thy-1+ DEC) were examined. Four Thy-1 + DEC clones which were established from athymic nude mice exhibited spontaneous or lectin-redirectable cytotoxic activity against some murine tumor cell lines In a 4 h ⁵¹Cr-release assay. A colorimetric assay for benzyloxycarbonyl-L-lysine-thiobenzyl ester esterase revealed a strong serine esterase activity expressed in all cell clones. In addition, Northern blot analysis using a murine perforin cDNA probe revealed that all four Thy-1 + DEC clones expressed abundant mRNA for perforin, as do most killer T cells. More Importantly, immunocytochemical staining with an anti-perforin monoclonal antibody revealed that not only all four Thy-1 + DEC clones but also a part of freshly isolated Thy-1 + DEC from normal and nude mice contained perforin. These results demonstrate that Thy-1 + DEC exhibit typical killer cell characteristics In vitro and in vivo. These data also suggest that Thy-1 + DEC may play a cytotoxic role in protecting the integrity of skin from infection or neoplastic transformation.