Ultraviolet B radiation upregulates the production of macrophage migrationinhibitory factor (MIF) in human epidermal keratinocytes

Human epidermal cells are capable of secreting various cytokines with immun ologic, inflammatory, and proliferative properties. In a previous study, by reverse transcription-polymerase chain reaction and immunohistochemical an alysis, we have shown that human epidermal keratinocytes express macrophage migration inhibitory factor and identified its presence in the cytoplasm, In this study, we detected an increased serum macrophage migration inhibito ry factor level by enzyme-linked immunosorbent assay after a single total-b ody ultraviolet B exposure in vivo, indicating that human keratinocytes res pond and release this cytokine in response to ultraviolet B irradiation. Mo reover, we evaluated the effect of ultraviolet B on migration inhibitory fa ctor production in cultured human epidermal keratinocytes and epidermal she ets. The results of enzyme-linked immunosorbent assay and northern blot ana lyses showed that migration inhibitory factor production of cultured kerati nocytes was increased by ultraviolet B exposure. During the past few years, migration inhibitory factor was found to have a variety of biologic functi ons, such as being essential for T cell activation and induction of inflamm atory cytokines, In this context, these results should encourage further in vestigation on the pathophysiologic role of migration inhibitory factor in cutaneous inflammatory reactions and immune responses.