Nonspecific Crossreacting Antigen (NCA) in Human Mammary Carcinoma Extracts

Abstract

Human mammary carcinoma (HMC) homogenates from 28 patients and mammary hyperplasia (MH) homogenates from 20 patients undergoing reduction mammoplasty were used as antigens in preparing antibodies in rabbits. Crossed immunoelectrophoresis of HMC extracts against the corresponding antibodies revealed one major precipitate not present in MH. This antigen was present in separately prepared extracts of breast tissue from 3 out of 10 patients with HMC. Antibody titre was unchanged following absorption with MH, normal human liver, kidney, skin and serum. Immunochemical crossreaction with pregnancy zone proteins, alpha‐1‐fetoprotein, ferritin, lactoferrin, plasma, extracts of human placenta and fetal and adult liver did not occur. The antigen could not be demonstrated by rocket immunoelectrophoresis of sera from patients with HMC. Small amounts of the antigen were found in extracts from human spleen and renal carcinoma and larger amounts in extracts from human peripheral granulocytes, but not in preparations of mononuclear leucocytes (98% pure). Tandem crossed immunoelectrophoresis of extracts from HMC and carcino embryonic antigen against antibodies prepared against HMC revealed a reaction of partial identity between the two antigens, and antisera prepared against carcino embryonic antigen contained precipitating antibodies against the HMC antigen. The HMC antigen was eventually identified as nonspecific crossreacting antigen (NCA) described by other authors.