The specific innate immune receptor CEACAM3 triggers neutrophil bactericidal activities via a Syk kinase-dependent pathway
Article first published online: 13 APR 2007
Volume 9, Issue 9, pages 2167–2180, September 2007
How to Cite
Sarantis, H. and Gray-Owen, S. D. (2007), The specific innate immune receptor CEACAM3 triggers neutrophil bactericidal activities via a Syk kinase-dependent pathway. Cellular Microbiology, 9: 2167–2180. doi: 10.1111/j.1462-5822.2007.00947.x
- Issue published online: 30 JUL 2007
- Article first published online: 13 APR 2007
- Received 30 September, 2006; revised 26 March, 2007; accepted 27 March, 2007.
The human-restricted pathogens Neisseria gonorrhoeae, Neisseria meningitidis, Haemophilus influenzae and Moraxella catarrhalis colonize host tissues via carcinoembryonic antigen-related cellular adhesion molecules (CEACAMs). One such receptor, CEACAM3, acts in a host-protective manner by orchestrating the capture and engulfment of invasive bacteria by human neutrophils. Herein, we show that bacterial binding to CEACAM3 causes recruitment of the cytoplasmic tyrosine kinase Syk, resulting in the phosphorylation of both CEACAM3 and Syk. This interaction is specific for the immunoreceptor tyrosine-based activation motif (ITAM) in the CEACAM3 cytoplasmic domain. While dispensable for the phagocytic uptake of single bacteria by CEACAM3, Syk is necessary for internalization when cargo size increases or when the density of CEACAM-binding ligand on the cargo surface is below a critical threshold. Moreover, Syk engagement is required for an effective bacterial killing response, including the neutrophil oxidative burst and degranulation functions in response to N. gonorrhoeae. These data reveal CEACAM3 as a specific innate immune receptor that mediates the opsonin-independent clearance of CEACAM-binding bacteria via Syk, a molecular trigger for functional immunoreceptor responses of both the adaptive (TCR, BCR, FcR) and innate (Dectin-1, CEACAM3) immune systems.