Human cytotoxic T-lymphocyte (CTL) lines with specificity restricted for autologous squamous cell carcinoma of the head and neck (SCCHN) were established from peripheral blood lymphocytes obtained at the time of surgery and again at two different times after surgery from a patient with cancer of the tongue. The CTL lines were cultured in the presence of interleukin (IL) 2, IL4, and autologous tumor (AuTu) cell monolayers. All three lines were CD3+CD8+CD11b-HLA-DR+ T-cell receptor alpha/beta+. They were tested in 4-h51Cr release assays against SCCHN cell lines (n = 5) and a variety of nonsquamous human tumor (n = 5) and normal (n = 5) cell targets and was found to lyse only AuTu (PCI-50) and three allogenic SCCHN cell lines. Lysis of AuTu and the three allogenic SCCHN targets by the established CTL lines appeared to be major histocompatibility complex class I restricted, since it was blocked by monoclonal antibodies to class I histocompatibility complex antigens. The CTL lines proliferated in vitro in response to autologous PCI-50 or an allogenic SCCHN cell line (PCI-1). The lines have been maintained in culture in the presence of AuTu monolayers and retained cytotoxicity against AuTu for over 20 weeks. The AuTu (PCI-50) cell line was tested for in vitro sensitivity to cytotoxic or cytostatic effects of various effector cells, including the CTL lines. PCI-50 targets were resistant to lysis by resting human mononuclear cells but sensitive to IL2-activated natural killer cells in 4-h 51Cr release assays. In comparison with IL2-activated natural killer cells, the CTL line mediated lower levels of lysis against AuTu. Growth of PCI-50 cells in culture was significantly inhibited by a combination of gamma-interferon and IL2 or by high concentrations of tumor necrosis factor alpha. While supernants of IL2-activated natural killer cells were growth inhibitory, those of the CTL line were not. On the other hand, lysis of AuTu targets by the CTL line was increased by preincubation of the tumor cells with tumor necrosis factor alpha or gamma-interferon. These cytokines augmented expression of HLA-class I, HLA-class II, and intercellular adhesion molecule I, but not squamous cell carcinoma-associated antigens, E7 and A9, on PCI-50 cells. The CTL lines described are the first with restricted specificity for autologous SCCHN ever reported and their availability will facilitate studies of the AuTu T-cell response in head and neck cancer.