The present invention provides a monoclonal antibody which specifically recognizes CD27 containing an O-linked sugar chain to which galactose is not bound and binds to its extracellular region, or a method for using the same. The present invention can provide a monoclonal antibody or an antibody fragment thereof, which specifically recognizes a polypeptide encoded by CD27 gene containing an O-linked sugar chain to which galactose is not bound, and binds to its extracellular region a hybridoma which produces the antibody a DNA which encodes the antibody a vector which comprises the DNA a transformant obtainable by transforming the vector a process for producing an antibody or an antibody fragment thereof using the hybridoma or the transformant and a diagnostic agent or a therapeutic agent comprising the antibody or the antibody fragment thereof as an active ingredient.本發明提供一種特異性識別含有未結合半乳糖之O-結合型糖鏈的CD27且與該細胞外區域結合之單株抗體及其使用方法。根據本發明,可提供特異性識別含有未結合半乳糖之O-結合型糖鏈的CD27且與該細胞外區域結合之單株抗體或該抗體片段、產生該抗體之融合瘤、編碼該抗體之DNA、含有該DNA之載體、將該載體轉形而獲得之轉形體、使用該融合瘤或轉形體之抗體或該抗體片段之製造方法、以及含有該抗體或抗體片段作為有效成分之與CD27相關之疾病之診斷藥或治療藥。(無元件符號說明)
