Described herein are methods and transplant compositions for promoting or inducing organ transplant tolerance and/or immune tolerance by conditioning a recipient with radiation-free, low-doses of cyclophosphamide (CY), pentostatin (PT), and anti-thymocyte globulin (ATG) prior to transplantation of PD-L1+ donor-derived CD4+ T-depleted bone marrow cells. In certain embodiments, the methods may also include transplanting an organ, such as a solid organ, into the recipient. The transplant compositions may comprise a therapeutically effective amount of PD-L1+ donor-derived CD4+ T-depleted bone marrow cells and a donor organ.