EPIDERMAL PROTEIN-KINASE C-BETA(2) IS HIGHLY SENSITIVE TO DOWN-REGULATION AND IS EXCLUSIVELY EXPRESSED IN LANGERHANS CELLS - DOWN-REGULATION IS ASSOCIATED WITH ATTENUATED CONTACT HYPERSENSITIVITY

Treatment of mice with multiple topical applications of 12-O-tetradeca noylphorbol-13-acetate (TPA) or diacylglycerol resulted in a preferent ial decrease in epidermal protein kinase C-beta(2) (PKC-beta(2)) compa red with PKC-alpha as determined by western analysis. When PKC-alpha w as decreased by 40%, PKC-beta(2) could no longer be detected, suggesti ng that PKC-beta(2) is more sensitive to downregulation, and/or specif ic epidermal cell types that contain PKC-beta(2) are more sensitive to TPA/diacylglycerol. To address this issue, we isolated Langerhans cel ls (LCs) from epidermal cell suspensions with immunomagnetic beads and an antibody to the class II major histocompatibility complex, Norther n blot analysis revealed a PKC-beta(2) signal in isolated LCs that was 40-fold greater than that observed in unfractionated epidermal cells, and no PKC-beta(2) signal was detected in epidermal cells depleted of LCs, indicating that PKC-beta(2) is expressed exclusively in LCs with in the epidermis. Western blot analysis confirmed the presence of PKC- beta(2) in LCs, PKC-beta(2), was highly sensitive to downregulation, b ecause a single application of TPA resulted in a 90% loss of PKC-beta( 2) within 6 h without a decrease in the number of LCs, To determine wh ether the decreased level of PKC-beta(2) within LCs was associated wit h an alteration in contact hypersensitivity, we treated mice with only a single application of TPA, and 6 hours later mice were sensitized w ith 2,4-dinitrofluorobenzene on the same dorsal area. Subsequent chall enge revealed a 60% decrease in contact hypersensitivity in TPA-treate d mice, These data indicate that (i) within the epidermis, PKC-beta(2) is highly sensitive to downregulation and is exclusively expressed in LCs, and (ii) the downregulation of PKC-beta(2) is associated with im paired LC function with respect to contact hypersensitivity.