In this experimental study, we assessed the expressions of indolamine 2, 3-dioxygenase (IDO1), IDO2 and human leukocyte antigen-G5 (HLA-G5) inASCs isolated from breast cancer patients with different stages as well as normalindividuals, using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR).Immunomodulatory effects of ASCs on the expression of CD16, CD56, CD69, NKG2D,NKp30, NKG2A and NKp44 was also assessed in peripheral blood lymphocytes (PBLs)by flow-cytometry. The gene discussed is IDO1; the disease is breast cancer.