Diagnostic imaging of infection and thrombus using radiolabeled pap tides developed by the genetic engineering.

单链抗体由多肽组成，从单克隆抗体遗传分析，并与相应抗原反应。单链抗体的优点是：(1)对人体无免疫原性，(2)化学产生，(3)与原单克隆抗体对同一抗原应答。从与卵巢癌抗原CA125反应的小鼠抗体中获得单链抗体，用放射性碘-125碘化。但I-125标记的抗体不稳定，与CA125抗原的结合尚不确定。重链和轻链的结合还有待研究。而保留小鼠抗体抗原结合位点的嵌合抗体则用锝-99m和I-125标记成功。与NCA-95结合的嵌合抗体对表达癌胚抗原（CEA）的人白细胞和结直肠癌细胞有反应。在获得伦理委员会的临床使用许可后，标记的Tc-99m被安全使用，并且在患有可塑性贫血、骨髓纤维化和白血病的患者中非常有用。Tc-99m标记的NCA-95嵌合抗体在临床上也可用于感染部位和脓肿的定位。

Single chain atibody consists of peptides, genetically analyzed from monoclonal antibody, and is reactive with the corresponding antigens. The advantages of single chain antibodies are (1) no immunogenecity to humans, (2) chemically produced, and (3) responding to the same antigen with the original monoclonal antibody.Single chain antibody was obatained from the murine antibody reactive with ovarian cancer antigen CA125, and iodinated with radioiodine-125. However I-125 labeled antibody was not stable and its binding to CA125 antigen was not confirmed. Binding of heavy chain and light chain remains to be studied.In contrast, chimeric antibody which reserves the antigen-binding sites of murine antibody was successfully labeled with technetium-99m and I-125.Chimeric antibody reactive with NCA-95 bindis to human leukocytes and colorectal cancer cells expressing carcinoembryonic antigen (CEA). After getting the permission of clinical use from the ethical committee, Tc-99m labeled was safely administered and was very useful in patients with a plastic anemia, myelofibrosis and leukemia. Tc-99m labeled chimeric antibody to NCA-95 would be also clinically useful for the localization of infectious sites and abscess.