This proposal seeks to expand previous serological work in melanoma to include another more common malignancy - squamous cell carcinoma of the head and neck (SCCHN). By doing so we hope to begin to determine if our findings in melanoma are indicative of a more generalized phenomenon. In melanoma, antibody derived from immune complexes provides a readily accessible source for the isolation and study of physiologically relevant antibody and antigen. We have evaluated the incidence of antibody reactivity to SCCHN in 41 autologous systems. Antibody reactivity was detected in the sera of 24 patients tested. However, in 10 cases autologous antibody reactivity was detected only in undiluted sera precluding further analysis. Analysis of one high titer sera revealed an antigen expressed on 6 of 10 allogeneic SCCHN cell lines but not autologous fibroblasts or allogeneic melanoma cell lines. Because of the low titer an incidence of autologous antibody reactivity in native sera we have turned to dissociation of immune complexes by acidification and ultrafiltration of sera (AD&U). Twelve serum samples from 8 patients were subjected to AD&U. Prior to AD&U only 6 sera had autologous antibody reactivity. Following AD&U all 12 sera demonstrated enhanced antibody reactivity against SCCHN. Specificity analysis of one serum sample after AD&U revealed an antigen common to SCCHN cell lines as well as melanoma, glioma, renal and colon carcinoma cell lines. Serial studies of antibody reactivity in 4 autologous SCCHN systems have revealed correlations with clinical course. These findings suggest that circulating immune complexes in SCCHN may provide a reservoir of antibody with potential diagnostic and therapeutic applications. Through the combined resources available at the Universities of Pittsburgh and Michigan we are in a unique position to evaluate the role of host-derived antibody reactivity in SCCHN in both native and immune complex-dissociated sera. Serologic studies will be performed utilizing sensitive microserological assays. Serial studies will allow correlations between antibody reactivity, clinical course and prognosis. Immunochemical analysis will involve isolation of cell acid dissociated ultrafiltrate. Subsequent analysis will be undertaken by polyacrylamide gel electrophoresis with blotting and detection using double antibody. Antigens thus detected will subsequently be subjected to sequence analysis on a gas phase sequenator. Analysis of SCCHN antigens that are immunogenic to the host may provide additional insight into the nature of the host tumor interaction with implication for host defenses and immunotherapy.