Analysis of macrophages and neutrophils infiltrating murine mammary carcinoma sites within hours of tumor delivery.

Here we used three different murine mammary carcinomas to study the immune environment associated with early tumor sites. While it was not surprising that the early immune response was predominated by macrophages and neutrophils, there were some novel findings at this early stage of disease. For instance, the macrophages and neutrophils expressed a mixed cytokine profile with TNF-α and TGF-β both produced at appreciable levels. Moreover, while the cells retained their phagocytic capacity, production of reactive oxygen species by the macrophages and neutrophils was in decline. Alterations in the metabolic profile of the tumor associated macrophages were also evident with a decrease in the ATP production rate, and a higher dependence on oxidative phosphorylation for ATP production. Collectively, these data indicate a mixed phenotype of tumor-associated macrophages and neutrophils evident within hours of murine mammary carcinoma delivery.