Malignant mesothelioma associated antigens recognized by tumor infiltrating B cells. -usefulness of antibody titer to the antigens -

恶性胸膜间皮瘤早期诊断困难，目前尚无公认的治疗方法。本研究通过异种移植SCID小鼠模型，从恶性间皮瘤的肿瘤浸润性B淋巴细胞(TIB)中获得肿瘤特异性抗体，并将TIB产生的免疫球蛋白应用于重组表达克隆法(SEREX)的血清学鉴定。5例恶性间皮瘤患者的手术标本建立了肿瘤细胞系，并将这些间皮瘤组织移植到SCID小鼠皮下，每隔2周采集血样。建立了两个间皮瘤细胞系K921MS0和L324MSO。以恶性间皮瘤细胞系(K921MS0)为材料，构建了人恶性间皮瘤细胞系的cDNA文库。用间皮瘤组织移植的SCID小鼠血清对文库进行免疫筛选。免疫反应性基因克隆…进一步亚克隆，利用数据库进行同源检索。对恶性间皮瘤患者血清中抗已鉴定抗原的抗体滴度进行分析，免疫组织化学染色显示肿瘤组织中有B淋巴细胞的浸润。在所有SCID小鼠血清中均可检测到人免疫球蛋白抗体(范围为134~24000μg/ml)。用来自TIB的抗体鉴定了11种抗原。6种抗原在恶性间皮瘤中呈高表达。抗这6种抗原的抗体不仅在SCID小鼠血清中检测到，而且在间皮瘤患者的血清中也能检测到。在12例间皮瘤患者中，7例检测到抗基因-X抗体，11例检测到凝血酶敏感蛋白-2抗体，提示肿瘤组织中的B细胞已经致敏，并产生了抗肿瘤相关抗原的抗体。在SEREX定义的抗原中，有两个抗原在恶性间皮瘤中过表达，并且在间皮瘤患者中检测到的抗体比例高于正常健康人。这两种抗原可作为诊断恶性间皮瘤的肿瘤标志物。较少

Malignant pleural mesothelioma is difficult to be diagnosed at early stage and universally accepted therapy has not been established. In this study, we tried to obtain tumor specific antibody derived from tumor infiltrated B lymphocytes (TIB) in malignant mesothelioma by using xenotransplanted SCID mice model, and applied TIB-produced IgG to serological identification of antigens by recombinant expression cloning method (SEREX).Surgical specimens from 5 patients with malignant mesothelioma have been tried to establish tumor cell lines, and also these mesothelioma tissues were engrafted subcutaneously in SCID mice and blood samples were obtained every 2 weeks after xenotransplantation. Two mesothelioma cell lines have been established (K921MS0 and L324MSO). cDNA library was constructed from a tumor cell line (K921MS0) of malignant mesothelioma. Immunoscreening of the library was performed using the serum from SCID mice transplanted with mesothelioma tissues. Immuno-reactive cDNA clones … More were subcloned, and analyzed using database for homology search. Antibodies titers against the identified antigens were analyzed in sera of patients with malignant mesothelioma.Immunohistochemical staining revealed that B lymphocytes infiltrated in tumor tissues. In all SCID mouse serum, human IgG antibody could be detected (ranged from 134 to 24000μg/ml). By using antibodies derived from TIB, 11 antigens were identified. Six antigens showed over expression for malignant mesothelioma. Antibodies against the 6 antigens could be detected not only in serum of SCID mouse but also in sera of mesothelioma patients. Among them, antibody against Gene-X was detected in 7 out of 12 mesothelioma patients, and antibody against Thrombospondin-2 was detected in 11 out of 12 mesothelioma patients.Our results suggest that the B cells infiltrated in the tumor tissues have been sensitized and produced antibody against tumor associate antigens. Among the SEREX defined antigens, 2 antigens (Gene-X and Thrombosponddin-2) were overexpressed in malignant mesothelioma, and antibodies against them could be detected in higher proportion of mesothelioma patients than normal healthy persons. These two antigens could be used as tumor markers for diagnosis of patients with malignant mesothelioma. Less