Immunohistochemistry (IHC) is a method to detect antigen or hapten in tissue section cells by using the specific combination of antibody and antigen in biological tissue. IHC is an important application of monoclonal and polyclonal antibodies, which can be used to determine the tissue distribution of antigens of interest in health and disease. It is widely used in cancer diagnosis because specific tumor antigens are de novo expressed or up-regulated in some cancers. In addition, IHC plays an important role in pathology, especially in tumor pathology, neuropathology and blood pathology.