Culture supernatant collected from ALK⁺ALCL cell lines up-regulates IL-8 secretion and NF-κB activation by keratinocytesviaHMGB-1 secretion. Culture supernatants were collected from keratinocytes (HaCaT) or ALK⁺ALCL (Karpas-299 and Su-DHL-1) cells (A) and HaCaT cells exposed to Karpas-299 and SU-DHL-1 cell line supernatants for 24 hours; and (B) IL-8 production was measured by ELISA. IL-8 mRNA levels were also evaluated by qRT-PCR in Karpas-299 (Karpas), SU-DHL-1 and HaCat (keratinocytes) cell lines (A). (C) Western blotting was performed to monitor Ser⁵³⁶ phosphorylation of NF-κB p65 from keratinocytes exposed to Karpas-299 or SU-DHL-1 cell culture supernatants for 24 hours or those exposed to DMEM as a control. qRT-PCR (D) and Western blotting (E) were performed to determine IL-8 mRNA levels and NF-κB activation in keratinocytes treated by the rhHMGB-1 cytokine or not (PBS). Results are expressed as the mean ± SD of 3 independent experiments done in triplicate. *P < .05 and **P < .01 by Student t test.