Protective effects of interferon-gamma on squamous-cell carcinoma of head and neck targets in antibody-dependent cellular cytotoxicity mediated by human natural killer cells

An in vitro model of antibody-dependent cellular cytotoxicity (ADCC) was established, using squamous-cell carcinoma of the head and neck (SCCHN) targets,human/mouse chimeric monoclonal antibodies (cMAbs) SF-25 and 323/A3 and human peripheral blood mononuclear cells (PBMC). We previously showed that natural killer (NK) cells are the main effector population mediating ADCC in the presence of the cMAbs. ADCC was significantly inhibited by the overnight pre-treatment of SCCHN targets with exogenous interferon-gamma (IFN-gamma). This inhibition was dose-dependent, reproducible and consistently observed with various SCCHN cell lines. SCCHN cells pre-treated with IFN-gamma had a significantly higher expression of intercellular adhesion molecule-I (ICAM-I) and major histocompatibility complex (MHC) class I antigens compared with untreated target cells. No differences in expression of the SCCHN-associated antigens on these targets or in the formation of NK-SCCHN conjugates were found, using flow cytometry. IFN-gamma-pre-treated SCCHN cells were less effective in competing with untreated targets in cold target inhibition assays and in inducing cytokine production from NK cells in co-incubation experiments. Protective effects of IFN-gamma on target cell sensitivity to lysis were blocked by pre-treatment of target cells with actinomycin-D or cycloheximide. The susceptibility of the target cells was restored by removal of MHC class I antigens from their surface by acid stripping before ADCC. Our results suggest that the decreased ADCC seen with SCCHN targets pre-treated with IFN-gamma is related to post-binding events, possibly altered signaling from targets to effector cells, and requires protein synthesis in the target cells.

Perspectives of monoclonal antibodies for detection and treatment of head and neck tumours

Monoclonal antibodies (mabs) are potentially powerful tools for the detection and treatment of cancer. To date, only a limited number of mabs are available to head and neck cancer. We produced 5 different groups of mabs to head and neck cancer. These mabs were characterized for their reactivity tumour and non-tumour tissues. Furthermore, biochemical elucidation of recognized antigens was provided. In animal studies the effectiveness of mabs for diagnoses and therapy of cancer is clearly demonstrated. The first results of a clinical study for the detection of head and neck cancer with mabs are shown. Finally, the future of mabs in clinical oncology is discussed.

Production of a monoclonal antibody (K 931) to a squamous cell carcinoma associated antigen identified as the 17-1A antigen

During our efforts to develop monoclonal antibodies (MAbs) to tumor associated surface antigens of squamous cell carcinomas of the head and neck, monoclonal antibody K 931 was produced. The high affinity antibody (Ka 5.0 x 10(10) M-1) showed reactivity with 58 out of 62 squamous cell carcinomas of the head and neck. In contrast normal squamous epithelium as found in epidermis, oral cavity, epiglottis, pharynx, larynx and esophagus did not express the antigen. All other tested epithelial (simple and transitional) tissues did express the antigen, but non-epithelial tissues were negative. Further characterization revealed that the antigen represents the 17-1A antigen. A not earlier reported, enhanced expression of the 17-1A antigen was observed among some primary and all metastatic SCC.