PD1+ Cells in Pediatric Classical Hodgkin Lymphoma is Associated with Better Outcome

Classical Hodgkin lymphoma (cHL) is characterized by few neoplastic cells in a background of inflammatory cells. Many studies have described the T cell composition of tumour microenvironment in adult cases and we have demonstrated differences between pediatric and adult cHL in this respect. Two studies recently described that high numbers of PD1+ cells were associated with worse survival in adult cHL. PD1 is a receptor expressed by CD8+ and CD4+ T cells upon activation, as well as by T follicular helper cells, exhausted CD8+ T cells and effector memory CD8+ T cells. The objective of this study was to evaluate PD…