242 Increased expression of inducible co-stimulator and inducible co-stimulator ligand in cutaneous t-cell lymphoma

Inducible co-stimulator (ICOS), a member of the CD28 coreceptor family, is costimulatory immune checkpoint receptor expressed on activated T-cells. Its ligand, ICOS ligand (ICOSL), antigen-presenting cells such as B cells. The ICOS-ICOSL axis plays an essential role in survival memory and effector T-cells responses, engagement by ICOSL induces proliferation, survival, cytokine production. Although their roles carcinomas are still subject investigation, expression cutaneous T-cell lymphoma (CTCL) has been detected. However, detailed CTCL remain to be seen. In this study, we investigated further CTCL, represented mycosis fungoides Sézary syndrome. Quantitative RT-PCR assay immunohistochemistry showed increased lesional skin reflected disease severity. Flow cytometric analysis that cell lines co-expressed ICOSL. Anti-ICOS-neutralizing antibody anti-ICOSL-neutralizing inhibited proliferation both vitro vivo. Anti-ICOSL-neutralizing also induced apoptosis suppressed CCR4 lines, which CCR4-CCL17-mediated migration. These results suggest may play pathogenesis targeting would new strategy for treating CTCL.