Microchimerism in Living Related Renal Transplants / 대한이식학회지

ABSTRACT

BACKGROUND: Immune tolerance is regarded as the goal of the organ transplantation (TPLx), but the mechanism of tolerance induction remains to be established. Microchimerism (MC) development in long-surviving recipients after solid organ TPLx might be linked to tolerance. OBJECTIVE: We investigated the development and clinical relevance of donor specific MC in living related renal transplants with good graft function more than 3 years after TPLx. The relationship between MC and mixed lymphocyte reaction (MLR) hyporeactivity was also evaluated. MATERIALS AND METHODS: Eighteen recipients were included in this study among recipients whose renal function were stable for more than 3 years and have at least one mismatch of HLA DR loci. Donor-specific MC was examined with nested PCR method using HLA DRB1 gene probe in DNA extracted from peripheral blood and forearm skin tissue samples. Mean age at TPLx was 28.9 yrs (range 13~42 yrs) and mean follow-up period was 67.4 months (range 36~173 mos). Male to female ratio was 117. Acute rejection occurred in 4 and were reversed with steroid pulse therapy. All donors were alive (parent8, sibling9, offspring1). Immunosuppression regimens were CSA(+)PDS in 11, AZA PDS in 1, AZA CSA(+)PDS in 5, and CSA monotherapy in 1. Mean serum BUN/Cr at the point of this study were 22.2+/-6.7 / 1.54+/-0.81 (mg/dL). The sensitivity of nested PCR using HLA DRB1 probe was 1/105~1/106. RESULTS: Donor-specific MC was detected in 6 (33.3%) (5 in blood, 5 in skin tissue). Nested PCR method was more sensitive than single round SSP-PCR method which showed only 2 positive recipients (11.1%). Two of four acute rejection experienced recipients were MC positive. Recipients were divided into two groups according to the follow-up period of 5 years. Two groups showed equal number of MC positivity. MLR was decreased in a group of more than 5 yrs follow-up. However, there was no difference in the decrement of MLR between MC positive and negative groups. CONCLUSION: MC was detected in 33.3% patients with nested PCR method. Since the MC positivity and MLR hyporesponsiveness shows no relationship, the significance of MC relevant to tolerance is to be determined through further study.