• Pancreatic Cancer

Myeloid-derived suppressor cells (MDSC) represent an immune cell subset with profound immune suppressor function. Initially described in 1978 as natural suppressor cells, this cell type has gained significant attention in recent years not only among tumour immunologists but also among medical oncologists interested both in developing new immune-based antitumour strategies and trying to understand how conventional non-immunological therapies affect antitumour immune responses.1 MDSC represent a mixture of immature cell types that accumulate in tumour-bearing mice and patients with cancer. Tumour-derived factors block the maturation of myeloid cells at different stages, leading to accumulation of these cells in tumours, as well as in the periphery. At least two different subsets of MDSC have been described in mice and men: monocytic and polymorphonuclear granulocytic MDSC, which can be identified as CD14⁺HLA-DR^lo/neg and lin^negCD11b⁺HLA-DR^neg in patients2 and as CD11b⁺Ly6G⁺ Ly6C^low or CD11b⁺Ly6G^neg Ly6C^hi in mice.3

An accumulation of MDSC has been described in multiple models of pancreatic cancer. We have been able to demonstrate an accumulation of MDSC in mice with premalignant lesions.4 Similarly, an accumulation of MDSC, regulatory T cells and tumour-associated macrophages has been described in KC mice, …