The invention discloses a high affinity antibody for recognizing CD39. The antibody can neutralize ATPase activity of CD39 on CD39 expressing cells. Such antibodies can be used to treat cancer and other diseases mediated by CD39 activity.本發明公開識別CD39的高親和力抗體。所述抗體能夠中和表達CD39的細胞上的CD39的ATP酶活性。這樣的抗體可用於治療由CD39活性介導的癌症和其他疾病。