The Status of Microchimerism in Long-Term Survivors After Living Related Kidney Transplantation

To determine the potential relevance of microchimerism to the long-term outcome of renal allograft, the frequency of microchimerism in kidney transplant recipients with graft function for 15 years or longer were analyzed. Of 104 recipients who underwent kidney transplantation between 1971 and 1980, 27 renal allografts (26%) are still functioning. Of these functioning grafts, 13 recipients whose donors were still alive and collaborative were investigated for the presence of microchimerism in the peripheral blood and for their immunological status. Microchimerism was tested using polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) method. To test the sensitivity of PCR-SSCP, peripheral blood obtained within five weeks after transplantation (four kidney, three liver) was also examined. Microchimerism was detectable in five patients within five weeks after transplantation (kidney 3/4, liver 2/3), while microchimerism was detected in only one recipient (1/13) of the patients with functioning grafts more than 15 years after transplantation. In this chimeric patient, mixed lymphocyte response (MLR) revealed a high responsiveness against donor antigen. In contrast, some patients without chimerism showed donor specific hyporesponsiveness in the MLR assay and did not develop anti-donor antibody by the flowcytometric analysis. Microchimerism is uncommon in the long-term survivors with functioning kidney grafts and was not related to donor specific unresponsiveness