Real F X, Mattes M J, Houghton A N, Oettgen H F, Lloyd K O, Old L J
J Exp Med. 1984 Oct 1;160(4):1219-33. doi: 10.1084/jem.160.4.1219.
Analysis of the humoral immune response of patients with melanoma has identified a small group of individuals with antibody to cell surface antigens that are restricted to autologous melanoma cells. These antigens, referred to as Class I or unique tumor antigens, are demonstrated by reactions between serum and cultured melanoma cells from the same patient and absorption tests with autologous and allogeneic normal and malignant cells to determine antibody specificity. Five Class 1 melanoma antigens have been defined to date, but insight into the nature of these antigens has been limited because antibodies identifying these antigens lacked detectable immunoprecipitating activity. We have now defined a Class 1 melanoma antigen (designated FD) that is immunoprecipitated by autologous antibody. FD antigen is identified by an IgG antibody present in the sera of patient FD, and peak titers of this antibody in tests with cultured autologous melanoma cells are in the range of 1:2048. By absorption tests, FD antigen could not be detected on any other cell type, including 33 allogeneic melanomas. Prolonged culture of FD melanoma cells resulted in decreased expression of FD antigen, but sublines could be obtained with stable antigen expression. FD antigen is trypsin and heat sensitive, neuraminidase resistant, and is shed in the culture medium. Immunoprecipitation of 125I-labeled cell membrane preparations revealed a 90,000 dalton component of pI 5.5. Serum immunoprecipitating activity could be absorbed by autologous melanoma cells but not by autologous B cells or allogeneic cell lines. A component of the same molecular mass could be precipitated from lysates of cells metabolically labeled with [3H]mannose. The membrane form of the FD antigen binds strongly to Con A-Sepharose and can be eluted with methyl-alpha-D-mannoside. The identification of a precipitating Class I antigenic system of melanoma facilitates efforts to generate monoclonal antibodies to this tumor antigen and to clone its coding sequence.
对黑色素瘤患者体液免疫反应的分析发现，一小部分个体产生了针对细胞表面抗原的抗体，这些抗原仅限于自体黑色素瘤细胞。这些抗原被称为I类或独特肿瘤抗原，通过同一患者血清与培养的黑色素瘤细胞之间的反应以及用自体和异体正常及恶性细胞进行的吸收试验来证明抗体特异性，从而得以鉴定。迄今为止，已确定了五种I类黑色素瘤抗原，但由于识别这些抗原的抗体缺乏可检测的免疫沉淀活性，对这些抗原性质的了解有限。我们现在已经确定了一种I类黑色素瘤抗原（命名为FD），它可被自体抗体免疫沉淀。FD抗原由患者FD血清中的IgG抗体识别，在用培养的自体黑色素瘤细胞进行检测时，该抗体的峰值滴度在1:2048范围内。通过吸收试验，在任何其他细胞类型上均未检测到FD抗原，包括33种异体黑色素瘤。FD黑色素瘤细胞的长期培养导致FD抗原表达下降，但可以获得具有稳定抗原表达的亚系。FD抗原对胰蛋白酶和热敏感，对神经氨酸酶有抗性，且会释放到培养基中。对125I标记的细胞膜制剂进行免疫沉淀，显示出一个分子量为90,000道尔顿、等电点为5.5的成分。血清免疫沉淀活性可被自体黑色素瘤细胞吸收，但不能被自体B细胞或异体细胞系吸收。用[3H]甘露糖代谢标记的细胞裂解物中可沉淀出相同分子量的成分。FD抗原的膜形式与伴刀豆球蛋白A-琼脂糖强烈结合，可用甲基-α-D-甘露糖苷洗脱。黑色素瘤沉淀性I类抗原系统的鉴定有助于生成针对该肿瘤抗原的单克隆抗体并克隆其编码序列。
