PROBLEM TO BE SOLVED: To provide medicaments comprising antibodies binding to phospholipase D4 (PLD4) as well as a method using the medicaments for detecting and suppressing activated B cells, and further provide therapy of auto-immune diseases and allergosis, resulting from the active-repressing function.SOLUTION: A monoclonal antibody binding to the extracellular domain of PLD4, or a fragment containing an antigen-binding region thereof, is used as an active ingredient.SELECTED DRAWING: NoneCOPYRIGHT: (C)2020,JPO&INPIT【課題】ホスホリパーゼＤ４（ＰＬＤ４）に結合する抗体を含む医薬の提供、並びに当該医薬を用いた活性化Ｂ細胞の検出及び抑制。さらに、その活性抑制機能に起因する、自己免疫疾患ならびにアレルギー疾患の治療。【解決手段】ＰＬＤ４の細胞外ドメインに結合するモノクローナル抗体、又はその抗原結合領域を含む断片を医薬として用いる。【選択図】なし
