Biochemical and biological properties of tumor-associated antigen of bovine leukemia cells

流行性牛白血病(EBL)是由牛白血病病毒(BLV)引起的淋巴增生性疾病。肿瘤细胞表面有肿瘤相关抗原(TAA)。已获得13株鉴定EBL细胞TAA的单抗。用这些单抗对TAA的性质进行分析。根据13株单抗对19个肿瘤的反应性，将TAA分为三组：共同TAA组、部分共同TAA组和个别不同TAA组。TAA与Lentil Lectin-Sepharose4B柱结合，是一种糖蛋白。常见的TAA分子质量为74,000(74K)，分子上至少有两个独立的抗原区共存。部分常见的TAA分子量为64K，至少有4个独立的抗原区。不同的TAA位于不同于部分共同TAA的分子上，其相对分子质量为64K。2.证实了C143与EBL肿瘤细胞体内识别的共同TAA结合的特异性。将~&lt；125&gt；I标记的C143F(ad‘)_2片段注射到荷牛淋巴样肿瘤细胞的裸鼠体内。放射免疫核素扫描显示，这些片段优先定位于肿瘤组织，而不是正常组织。3.检测了C143的抗肿瘤作用。裸鼠每隔一天注射C143(200微克微克)至移植瘤后37天，与对照组相比，肿瘤生长受到明显抑制(P<0.05)。

Enzootic bovine leukosis (EBL) is a lymphoproliferative disease caused by bovine leukemia virus (BLV). The neoplastic cells have tumor-associated antigens (TAA) on their cell surface. Thirteen monoclonal antibodies that identified TAA on EBL cells have been obtained. The properties of the TAA were analyzed by using these monoclonal antibodies. The results obtained in this studies are summerized as follows; 1. According to the reactivities of 13 monoclonal antibodies with 19 individual tumors, TAA were classified into 3 groups: common TAA, partially common TAA and individually distinct TAA. TAA bound to Lentil Lectin-Sepharose 4B column and were thus a glycoprotein. Common TAA with a molecular weight (M.w) of 74,000 (74K) had at least 2 independent antigenic regions coexisting on the molecule. The partially common TAA with a M.w of 64K had at least 4 independent antigenic regions. Individually distinct TAA with a M.w of 64K was located on molecule different from that of the partially common TAA. 2. The specificity of c143, recognized common TAA, binding in vivo for EBL tumor cells was demonstrated. The ^<125>I-labeled c143 F(ad')_2 fragments were injected into athymic mice bearing bovine lymphoid tumor cells. The fragments became preferentially localized in tumor tissues but not in normal tissues, as determined by radioimmunoscintigraphy. 3. An antitumor effect of c143 was tested. Nude mice injected with c143 (200<micrn>g) every other day until 37 days after the tumor transplantation showed significant inhibition of tumor growth when compared with control groups (p<0.05).