Macrophages in multiple myeloma

• Tumor associated macrophages (TAMs) are a rich source of pro-angiogenic cytokines and growth factors.
• A relationship between TAMs counts, rate of tumor growth and density of vascularization has been demonstrated in tumors.
• Angiogenesis is a constant hallmark of multiple myeloma (MM) progression and has prognostic potential.
• In MM, plasma cells secrete angiogenic cytokines that induce TAMs to secrete their own angiogenic factors.
• TAMs have become an appealing target for anti-angiogenic therapies in MM.

Tumor associated macrophages (TAMs) are a rich source of pro-angiogenic cytokines and growth factors, and a relationship between the TAMs content, the rate of tumor growth and the extent of vascularization has been shown in several tumors. In this article, we have summarized the literature and our data concerning the involvement of TAMs in angiogenesis occurring in multiple myeloma. Finally, therapeutic aspects concerning the potential role of molecules which inhibit macrophage recruitment in the tumor side are also discussed.