Tumour-associated macrophages are related to progression in patients with metastatic melanoma following interleukin-2 based immunotherapy

The aim of the present study was to analyze whether leukocyte subsets in peripheral blood and tumour biopsies obtained before treatment were able to predict response or survival in patients with metastatic melanoma following Interleukin-2 (IL-2) based immunotherapy. Flow cytometry was performed on peripheral blood for CD4+ T cells, CD8+ T cells and CD56+ natural killer (NK) cells. Immunohistochemical analyses were used to identify CD4+ T cells, CD8+ T cells, CD57+ NK cells and CD64+ (macrophages) cells in tumour biopsies. High numbers of tumour-associated CD64+ macrophages in tumour biopsies were statistically significantly associated with poor response to treatment. Our data suggest that tumour-associated macrophages may correlate negatively with response, which may be of biological importance for IL-2 based immunotherapy of malignant melanoma.