Monoclonal antibody against human squamous-cell-carcinoma-associated antigen

Mouse monoclonal antibody (MAb) 3F8E3 (lgG3k) was developed against the head and neck cancer cell line LICR-LON-HN2. Subjected to indirect immunofluorescence, the MAb reacted exclusively with SCC cell lines and showed no reactivity with normal or transformed mouse and human non-SCC cell lines and hematopoietic cell lines. The radiolabeled MAb showed an affinity constant of 1.8 × 108 M-1 with HN2 cells and identified 2.07 × 104 sites/cell by Scatchard analysis. It identified 2 peptides from membrane extracts of HN2 cells by Western blotting. Avidin-biotin-complexed im-munoperoxidase staining on cryostat sections of tumors from various tissues revealed that 3F8E3 reacted mainly with the membrane antigens of well differentiated SCC cells of oral cavity, larynx, esophagus, lung, uterine cervix, metastatic nodes of patients with oral cancer, and dysplastic cells in oral leukoplakia. The MAb did not react with poorly differentiated cells of Ca esophagus, adenocarcinoma of breast, stomach and colon, renal-cell carcinoma and soft-tissue sarcoma