Abstract: A method for predicting ADCC activity in a subject, the method comprising the steps of: (a) preparing a biological sample from the subject, said sample including a leukocyte, (b) bringing a portion of the biological sample and an antibody into contact with each other, (c) detecting expression of at least one marker of ADCC activity selected from the group consisting of tumor necrosis factor super family 15, chemokine CXCL3, and interleukin 6 in the leukocyte in (i) the portion of the sample brought into contact with the antibody and in (ii) another portion of the sample not brought into contact with the antibody, (d) comparing an expression level in portion (i) with the expression level in portion (ii); and (e) predicting presence of the cytotoxic activity when the expression level in portion (i) is higher than the expression level in portion (ii)