[Comparative study of the resistance of CEA and NCA to acid proteases]

The non-specific cross reacting antigen (NCA), characterized by its cross reaction with the carcinoembryonic antigen of the digestive system (CEA), is present in human polymorphonuclears and macrophages. We showed that this antigen is not damaged by endocellular acid proteases (cathepsine D and E), nor by pepsin: there is no change in the molecular weight, the electrophoretic mobility and the immunochemical reactivity of the enzyme treated NCA. These data make likely the hypothesis of NCA playing a role in the protection of polymorphonuclears and macrophages against their own proteases.