Carcinoembryonic antigen induces signal transduction in Kupffer cells

Carcinoembryonic antigen (CEA), an iptercellular adhesion molecule and a mediator of hepatic metastasis, is processed by an 80 kDa receptor on murine and human Kupffer cells in the liver. Activation of rat Kupffer cells in vitro by CEA via the 80 kDa receptor produced cytokines IL-1α and TNF-α which involved tyrosine phosphorylation. The peak response of TNF-α was 5.6 times greater than the corresponding IL-1α response and was associated with enhanced tyrosine phosphorylation of 108 and 125 kDa proteins. Lipopolysaccharide (LPS) treatment, on the other hand, phosphorylated two major proteins with MW of 93 and 119 kDa associated with the loss of phosphorylation from a 125 kDa protein. Results demonstrate that CEA-induced IL-1α and TNF-α production involves tyrosine phosphorylation and the signaling in CEA treated cells is different than that seen with LPS stimulation.