ISOLATION AND IDENTIFICATION OF HUMAN LUNG TUMOR-ASSOCIATED ANTIGENS

Abstract

Three human lung tumor-associated antigens (TAA) were identified in soluble and membrane-solubilized extracts of human squamous cell lung carcinoma with the use of antisera raised in rabbits. The antigens were identified and partially characterized by means of an agarose adsorption technique. These antigens, termed lung TAA 1, 2 and 3, are all soluble in 50% ammonium sulfate, are antigenically distinct, and do not cross-react with carcinoembryonic antigen or .alpha.-fetoprotein. Lung TAA 1 and 2 are oncofetal antigens demonstrable in soluble extracts from 24 wk old but not from 26 wk old fetal lungs. Rabbit antibodies to these lung TAA were not adsorbed by types A, B and O human red blood cells, serum proteins, and soluble or insoluble lung preparations. Of several commercial antisera to human proteins, none cross-reacted with lung TAA 1, but anti-human liver ferritin cross-reacted with lung TAA 2, and anti-human lactoferrin cross-reacted with lung TAA 3. Lung TAA 1 was partially adsorbed and cross-reacted with certain normal serum or plasma preparations used and appears to be a normal serum protein in Cohn Fraction IV-4. Lung TAA 2 and 3 appear only in lung tumor-soluble extracts, whereas the lung TAA 1 was demonstrable in soluble extracts of breast, colon, cervical and head and neck carcinoma. All may be tumor markers of value in immunodiagnosis.