Carcinoembryonic antigen-related cell adhesion molecule 8 (CEACAM8) also known as CD66b (Cluster ofDifferentiation 66b), is a human gene. In neutrophils, the CEACAM8 gene is primarily detected in the secondary granules within the cytoplasm, but it can also be found in lower amounts on the plasma membrane. The amount of CD67 on the plasma membrane is up-regulated upon granulocyte activation. CD67 has been located on the surface of neutrophilic and eosinophilic granulocytes at late stages of differentiation.