Two murine monoclonal antibodies against human lung cancer-associated antigens.

Two murine monoclonal antibodies, MAb 8 (immunoglobulin G3 kappa) and MAb 15 (immunoglobulin G1 kappa), were produced after immunization with TKB-2, a variant cell line of human small cell carcinoma of the lung. In enzyme-linked immunosorbent assay, these antibodies reacted with four major types of lung cancer cell lines and various extrapulmonary tumor cell lines. Immunohistological study, however, showed highly specific binding to lung cancers; MAb 8 bound to 68% of 65 lung cancers, and MAb 15 bound to 72% of them. Interestingly, both antibodies were more reactive with non-small cell than small cell lung cancers and bound most frequently to large cell carcinoma. Most extrapulmonary tumor tissues were negative in staining with a few exceptions; endodermal sinus tumor (two of two) was positive to both antibodies, breast carcinoma (one of five) to MAb 8, gastric carcinoma (one of three), and malignant melanoma (one of one) to MAb 15. Cross-reactions with normal tissues were limited; MAb 8 reacted with adult and fetal lung, and MAb 15 with esophagus and renal tubules. MAb 8 recognized a Mr 48,000 glycoprotein antigen (carbohydrates as its epitope), and MAb 15 recognized two proteins (Mr 85,000 and 45,000) (peptides as their epitopes). These two antibodies, detecting novel antigens extensively associated with and highly specific to lung cancers, are potentially useful for the study of lung cancer.