Immunocytochemical investigation of the tissue of origin of two lung cancer cell lines.

The constitutive cell types of the two lung cancer cell lines CaLu1 and CaLu3 have been investigated by immunocytochemical staining with markers for cytokeratins, vimentin, carcinoembryonic antigen and the epithelial cell epitope recognized by the monoclonal antibody Ber-EP4. The cells of both lines reacted with vimentin, with CAM 5.2, which is a marker for cytokeratins 8, 18 and 19, and with a specific marker for cytokeratin 19. CaLu3 cultures showed patchy staining, and CaLu1 none, when treated with a monoclonal antibody reactive with cytokeratins 13, 14 and 17. CaLu3 cells all reacted strongly with Ber-EP4 and the antibody to carcinoembryonic antigen, whereas CaLu1 gave a negative reaction with both these reagents. These results indicate that the CaLu3 line has retained antigens characteristic of some bronchial adenocarcinomata, and that the CaLu1 line was derived from a mesothelioma rather than a pleural metastasis of a squamous carcinoma.