The present invention provides a novel, engineered tri-chain antibody comprising three polypeptide chains, wherein the first polypeptide chain comprises a first heavy chain variable domain, the second polypeptide chain comprises a first light chain variable domain, and the first heavy chain variable domain pairs with the first light chain variable domain to form a first antigen binding site； and the third polypeptide chain comprises a single domain as a second antigen binding site and another single domain as a third antigen binding site. The invention also provides a polynucleotide encoding the tri-chain antibody, a vector comprising the polynucleotide, a host cell comprising the polynucleotide or the vector, an immunoconjugate comprising the tri-chain antibody, and a pharmaceutical composition comprising the tri-chain antibody or the immunoconjugate thereof, and a use of the tri-chain antibody for immunotherapy, prevention and/or diagnosis of a disease.本發明提供了一種新型的經人工設計的包含三條多肽鏈的三鏈抗體，其中第一多肽鏈包含第一重鏈可變結構域，第二多肽鏈包含第一輕鏈可變結構域，該第一重鏈可變結構域與第一輕鏈可變結構域配對形成第一抗原結合位點；且第三多肽鏈包含單結構域第二抗原結合位點和單結構域第三抗原結合位點。本發明還提供了編碼該三鏈抗體的多核苷酸、包含該多核苷酸的載體、包含該多核苷酸或載體的宿主細胞、包含該三鏈抗體的免疫綴合物和包含該三鏈抗體或其免疫綴合物的醫藥組成物、以及該三鏈抗體在疾病的免疫治療、預防和/或診斷上的用途。
