CD40 ligation inhibits trichilemmoma cell proliferation and induces IL-6 production

CD40 is a member of the tumor necrosis factor receptor superfamily expressed by B cells, monocytes, dendritic cells, epithelial cells, and hematopoietic progenitor cells. Recently, CD40 has been reported to also be expressed on human epidermal cells. We have elucidated the function of CD40 on epidermal tumor cells and have found that trichilemmoma (KTL-1) cells constitutively express CD40 and respond to CD40 ligation by anti-CD40 mAb (EA-5) with a significant decrease in proliferation. We were also able to demonstrate that KTL-1 cells respond to CD40 ligation by EA-5 with the up-regulation of interleukin-6 (IL-6) mRNA expression. Together, the results suggest that CD40 on KTL-1 cells may function to regulate their proliferation associated with the induction of IL-6 production.