Feinberg R F, Kliman H J, Bedian V, Monzon-Bordonaba F, Menzin A W, Wang C L
Department of Obstetrics and Gynecology, University of Pennsylvania Medical Center, Philadelphia 19104-4283, USA.
Am J Obstet Gynecol. 1995 May;172(5):1526-36. doi: 10.1016/0002-9378(95)90491-3.
Oncofetal fibronectin reactive with antibody FDC-6 has been associated with trophoblastic implantation and chorion structural stability. Abnormal release of this fibronectin into cervical and vaginal secretions has identified patients at risk for preterm labor and delivery. The aim of this study was to determine whether trophoblast-derived oncofetal fibronectin contains other novel epitopes distinct from the FDC-6 binding site.
Antitrophoblast fibronectin hybridomas were generated and screened by comparative immunoassays. One specific monoclonal antibody, X18A4, was identified and compared with antibody FDC-6 by immunocytochemical and immunoblot analyses. Both antibodies were also evaluated in "sandwich"-type double monoclonal immunosorbent assays.
X18A4 and FDC-6 bind avidly and noncompetitively to distinct epitopes within oncofetal fibronectin. They exhibit similar immunohistochemical staining of the extracellular matrix within placental tissue, ovarian epithelial tumors, and cultured trophoblasts. However, in contrast to FDC-6, X18A4 has no detectable binding activity to human plasma fibronectin, and its binding to oncofetal fibronectin was unaffected by enzymatic deglycosylation. Immunoblot analyses of oncofetal fibronectin proteolytic digests suggest that X18A4 binds near or within the alternatively spliced type III connecting segment domain.
X18A4 identifies and binds with high affinity to a new epitope within oncofetal fibronectin, distinct from the FDC-6 binding site. Because X18A4 displays no detectable binding to plasma fibronectin, it could be used as an important adjunctive antibody for enhancing the specificity of clinically based oncofetal fibronectin diagnostic assays.
与抗体FDC - 6反应的癌胚纤连蛋白与滋养层植入及绒毛膜结构稳定性相关。该纤连蛋白异常释放到宫颈和阴道分泌物中可识别出有早产和分娩风险的患者。本研究的目的是确定滋养层来源的癌胚纤连蛋白是否含有不同于FDC - 6结合位点的其他新表位。
制备抗滋养层纤连蛋白杂交瘤，并通过比较免疫测定进行筛选。鉴定出一种特异性单克隆抗体X18A4，并通过免疫细胞化学和免疫印迹分析将其与抗体FDC - 6进行比较。两种抗体还在“夹心”型双单克隆免疫吸附测定中进行了评估。
X18A4和FDC - 6分别与癌胚纤连蛋白内不同的表位紧密且非竞争性结合。它们在胎盘组织、卵巢上皮肿瘤和培养的滋养层细胞内的细胞外基质中表现出相似的免疫组织化学染色。然而，与FDC - 6不同，X18A4对人血浆纤连蛋白没有可检测到的结合活性，并且其与癌胚纤连蛋白的结合不受酶促去糖基化的影响。对癌胚纤连蛋白蛋白水解消化产物的免疫印迹分析表明，X18A4在选择性剪接的III型连接段结构域附近或内部结合。
X18A4识别并以高亲和力结合癌胚纤连蛋白内一个不同于FDC - 6结合位点的新表位。由于X18A4对血浆纤连蛋白没有可检测到的结合，它可作为一种重要的辅助抗体，用于提高基于临床的癌胚纤连蛋白诊断测定的特异性。
