1115P - The characterisation of Arginase-1 expressing myeloid-derived suppressor cells in advanced melanoma

Date 28 September 2014
Event ESMO 2014
Session Poster Display session
Topics Melanoma and other Skin Tumours
Translational Research
Presenter Christopher Bailey
Citation Annals of Oncology (2014) 25 (suppl_4): iv374-iv393. 10.1093/annonc/mdu344
Authors C. Bailey1, A. Jackson2, P. Patel2
  • 1Academic Unit Of Clinical Oncology, University of Nottingham, NG5 1PB - Nottingham/GB
  • 2Academic Unit Of Clinical Oncology, University of Nottingham, Nottingham/GB

Abstract

Aim

The role of myeloid derived suppressor cells (MDSC) in the regulation of the immune response to cancer is rapidly emerging. The heterogeneous nature of the population presents difficulties in defining the subtypes that may be important in tumour-induced immunosuppression of T-cell responses, however two distinct populations are of granulocytic (grMDSC) and monocytic subtypes (moMDSC). To characterise MDSC populations in melanoma, peripheral whole blood samples of patients with melanoma and healthy donors were compared for arginase-1 expression.

Methods

Intracellular multi-colour flow cytometry was used to qualify expression of arginase-1 amongst CD11b+CD15+ (grMDSC) and CD11b+CD14+HLA-DRlow (moMDSC) populations. Peripheral blood samples of 5mL were taken from patients with advanced melanoma and from healthy donors. Staining and acquisition of cell types took place within 2 hours of obtaining the blood samples.

Results

The expression of arginase-1 was significantly higher in the grMDSC population, when compared with moMDSC. This corresponded with a population expansion of CD11b+CD15+ in melanoma patients (p = 0.04). When testing for IL-10, there was no increased expression within CD11b+CD15+ or CD11b+CD14+HLA-DRlow, in healthy or melanoma patients. Interestingly, arginase-1 expression was present amongst healthy donors, and this weakly correlated with age (r = 0.33).

Conclusions

grMDSCs express more arginase-1 when compared to moMDSCs. A population expansion of grMDSC amongst melanoma patients when compared to healthy donors indicate an immunosuppressive response to melanoma. Age itself may facilitate the expansion of the MDSC population.

Disclosure

All authors have declared no conflicts of interest.