We are studying membrane antigens of human squamous cell cancer with the use of naturally occurring autologous antibodies from patients' sera, along with a set of other serologic reagents and monoclonal antibodies raised against cultured squamous cell lines. Twenty-eight squamous cell carcinoma cell lines have been established in our laboratory from tissues obtained from 23 patients. Antibody reactivity has been found against the autologous tumor cell line in 13 of 23 patients. One of these is of sufficient titer for detailed analysis. Four cell lines are available from this patient. UM-SCC-17A is derived from the primary laryngeal carcinoma, and UM-SCC-17B is derived from a lymph node metastasis removed during the same surgical procedure. Fibroblasts have been cultured from normal mucosa, and a B-lymphoblastoid line has been developed by Epstein-Barr virus transformation of the patient's peripheral blood lymphocytes. Antibody from this patient reacts with the UM-SCC-17A and -17B tumor cell lines but does not react with the normal fibroblasts (UM-NF-17).