Archives of dermatological research
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IL-18 is a pro-inflammatory cytokine of the IL-1 family involved in Th1/Th2 polarization. IL-18 is produced and stored as an inactive precursor (proIL-18) in several cells including keratinocytes, and thus appropriate processing is required to release its active form. In a previous study using recombinant protein, we demonstrated that granzyme B (GrB) cleaves proIL-18 into its active forms in a similar fashion as caspase-1 and human mast cell chymase. ⋯ The interaction between HaCaT cells and CTL co-culture increased the number of cytoplasmic GrB-positive HaCaT cells with limited endogenous GrB mRNA expression. The concentration of mature IL-18 levels increased in the co-culture supernatant. GrB from CTLs acts double roles to keratinocytes: a IL-18 converting enzyme and pro-apoptotic factor in the skin inflammatory diseases.