**3.2 Tumour-infiltrating immune cells in PCa**

Prostate cancer has a complex microenvironment which develops during the course of tumour development. Tumour cells are surrounded by endothelial cells of blood vessels, stromal fibroblasts, bone marrow-derived cells and lymphocytes. These cells produce growth factors and enzymes that enhance tumour growth and survival, aid stromaremodelling and recruit further immune cells into the tumour. The two main immune cell types infiltrating the tumour are lymphocytes and myeloid cells.
