A murine monoclonal antibody raised against human non-small cell carcinoma of the lung

Murine monoclonal antibodies (MAbs) reactive with human non-small cell carcinoma of the lung (NSCCL) were produced following immunization with a membrane preparation of Calu-3, a human adenocarcinoma of the lung cell line grown in nude mice. Positive hybrids unreactive with normal liver membranes and human peripheral white blood cells were selected for further testing. One MAb (RS5-4H6) recognized an antigen expressed in a variety of lung and other carcinoma cell lines as detected by flow cytometry. Immunohistology showed a selectivity for normal and neoplastic lung epithelium, as well as other cancers. The antigen was detected by immunohistology in 87% of tumor specimens derived from the lung, breast, colon, kidney, and ovary. Most other normal human tissues were not stained but occasional cells of the stomach, salivary and other glands, as well as kidney tubules were reactive. This MAb is an IgG1. Western blot analysis indicated that the antibody reacts selectively with an antigen greater than 300 kD. The antigen is resistant to neuraminidase treatment and periodate oxidation, but sensitive to pronase treatment, suggesting that the epitope is peptide in nature. This antibody may be potentially useful as a targeting agent for radioimmunodetection and immunoconjugate therapy.