The Human Reactive M1 vs M2 Macrophage IHC Antibody Sampler Kit provides an economical means of characterizing the extent of M1 and M2 macrophages in formalin-fixed, paraffin-embedded tissue samples.

Macrophages are myeloid cells of the innate immune system that are found in all human tissues in the body and exhibit anatomical and functional diversity. These heterogenous cells are derived from monocyte precursors in the blood that infiltrate into the tissues and differentiate in the presence of cytokines and growth factors. A spectrum of different macrophage phenotypes, or polarizations, have been described based on their secretory profiles, gene expression, and functions. Macrophages have great plasticity and can switch from one phenotype to another under different conditions. At the opposite extremes of this spectrum are so called M1, or classically activated phenotype, and M2 or alternatively activated phenotype. M1 macrophages are generally inflammatory and anti-tumor, while M2 macrophages, commonly referred to as tumor-associated macrophages (TAMs), are generally anti-inflammatory and pro-tumor. Relative contents of M1 and M2 macrophages in the tumor microenvironment may have prognostic values. Modulating macrophage polarization is actively pursued as a therapeutic intervention for many different diseases (1-6).
In humans, CD68 is considered a general marker for macrophages. CD11c, CD86, HLA-DRA, phospho-STAT1 (Tyr701), and others have been used as markers for M1 macrophages, while CD163, CD206, and others have been used as markers for M2 macrophages (7-10).