Immunohistochemical Assessment of Leukocyte Involvement in Angiogenesis

Angiogenesis is a hallmark of cancer and is important for tumor growth, development, and metastasis. Leukocytes, including neutrophils, eosinophils, basophils, lymphocytes, and monocytes, are found invading many solid tumors, and this inflammation is often associated with tumorigenesis. Tumor-associated macrophages have been shown to be involved in tumor migration and metastasis and are modulators of tumor vascularization. Tumor-associated macrophages are a source of angiogenic factors, and pro-inflammatory cytokines involved in angiogenesis, lymphangiogenesis, and metastasis. Here we describe a method of quantifying the number of macrophages and their class within tumor tissue which can be compared with tumor blood and lymphatic microvessel density as a measure of angiogenesis and lymphangiogenesis. Although not described in depth, application of the methodology is described for other leukocyte populations, such as tumor-infiltrating lymphocytes.