Donor-Specific Lymphocyte Proliferation (mixed lymphocyte reaction). Heparinized blood sample of recipient was collected before (day-35) and after (day + 30) the MSC-kidney transplantation. The recipients lymphocytes (responder) were co-cultured with irradiated donor lymphocytes (stimulator) for 4 days. Donor-specific recipients’ lymphocyte proliferation was determined by 3H-thymidine incorporation using a liquid scintillation counter (Beckman LS 6500; Beckman Instruments Inc., Fullerton, CA, USA). Proliferative response was represented by DPM. Plus signs indicate statistically significant induction of proliferative response (p < 0.05) compared to D-35 baseline activity. Asterisks indicate the statistical significance of decreased proliferative response compared to D-35 baseline activity (p < 0.05).