Carcinoembryonic antigen-related cell adhesion molecule 3 (CEACAM3)

Carcinoembryonic antigen-related cell adhesion molecule 3 (CEACAM3), also known as CD66d, is a transmembrane glycoprotein and a member of the immunoglobulin superfamily, expressed exclusively on human granulocytes. Unlike other CEACAM family members, CEACAM3 does not participate in cell-cell adhesion but serves as a specialized receptor facilitating rapid, opsonin-independent phagocytosis of certain human-specific bacterial pathogens by engaging its unique immunoreceptor tyrosine-based activation motif (ITAM) in the cytoplasmic domain. Upon pathogen binding, CEACAM3 triggers actin-dependent bacterial engulfment via activation of the small GTPase Rac and downstream effectors, contributing to innate immune defense. It is used as a granulocyte marker and has been studied as a prognostic indicator in certain cancers such as lung adenocarcinoma, although its main biological significance lies in host-pathogen interaction rather than as a classical therapeutic target.

Other names

CD66dCEA cell adhesion molecule 3CGM1W264W282CEAcarcinoembryonic antigen-related cell adhesion molecule 3carcinoembryonic antigen related cell adhesion molecule 3

Not a direct target of approved drugs, but drugs or antibodies could theoretically modulate phagocytosis or immune response by inhibiting or engaging CEACAM3. Bacterial proteins (such as adhesins) interact with CEACAM3 to mediate cell invasion and phagocytosis.