AU cell-surface antigen of human malignant melanoma: solubilization and partial characterization.

Abstract

AU antigen is defined by reactions of sera from patient AU with cell-surface antigens of cultured autologous melanoma cells . Past studies established that no available cell type other than AU melanoma expressed AU antigen. By use of antibody inhibition tests for antigen detection, limited papain digestion of AU melanoma cells was found to result in the solubilization of AU antigen along with p2-microglobulin (82m) and HLA allogeneic and xenogeneic specificities.Comparable papain treatment of other melanoma and nonmelanoma cell lines solubilized fl2m and HLA, but did not result in the release of antigen with AU reactivity. Maximum yield of AU antigen from AU melanoma cells was obtained after very short (5-15 min) digestion times in contrast to the more prolonged proteolysis required for maximum HLA and #2m release.AU antigen was not immunoprecipitated by rabbit antiserum against f2m or HLA under conditions leading to partial or complete removal of 02m and HLA. At least a proportion of the molecules with AU determinants appear to be glycoproteins, as indicated by specific affinity for Lens culinaris hemagglutinin (LcH). After affinity chromatography on LcH-agarose, the specific activity of AU antigen was increased 50-fold. As determined by gel filtration chromatography, AU antigen has a molecular weight in the range of 20,000-50,000. In a serological study of cultured melanoma cells from a series of 35

Prognostic role of antibody reactivity to melanoma.

“…Melanoma is a tumor in which immune factors have been implicated in the pathogenesis and natural history of the disease. Melanoma cell surface antigens of several degrees of restriction have been detected by antibody of autologous, allogeneic, and xenogeneic origin (2)(3)(4)(5)(6)(7)(8)(9)(10). Several of these melanoma cell surface antigens, which have been shown to be shared or common, have been detected upon a majority of melanomas studied.…”

Serial studies of autologous antibody reactivity to melanoma. Relationship to clinical course and circulating immune complexes.

“…In native sera, we and others have found low-titer autologous antibody to melanoma in one-third of melanoma patients (15)(16)(17)(18)(19). Our failure to detect autologous antibody to melanoma more fiequently led us to postulate that this might be due to circulating antigen and the formation of immune complexes.…”

Isolation and partial characterization of melanoma-associated antigens identified by autologous antibody.

“…The difficulty encountered by others in detecting and isolating autologous antigens has been attributed to a number of factors: loss of antigen expression in vitro, poor immunogenicity of the antigens, antigenic heterogeneity, insufficient antibody levels, and the failure to immunoprecipitate the antigens (17,24,31). This report and our previous studies (20,22,23) would suggest an alternative explanation.…”

“…Antibody against autologous tumor cell surface antigens was first reported by Carey et al (16,17) and Shiku et al (18,19) using sensitive microserologic assays and cultured tumor cells. Antigens described in those studies were divided into three classes: those that are restricted to the tumor of a single individual (class I); those that are shared among tumors of a similar histotype or ontogeny and rarely, if ever, found in nonneoplastic cells (class II); and those that are found in nonneoplastic cells as well as tumors (class III).…”

“…Only two successful immunochemical characterizations of class I melanoma antigens have been reported. Carey et al (17) partially characterized a 25,000-40,000-mol wt class I antigen (AU) by gel filtration chromatography. More recently, Real et al (24) reported a class I glycoprotein of 90,000 mol wt isolated by immunoprecpitation with autologous antibody and radiolabeled melanoma cells.…”