PERIPHERAL-BLOOD MICROCHIMERISM IN HUMAN LIVER AND RENAL-TRANSPLANT RECIPIENTS - REJECTION DESPITE DONOR-SPECIFIC CHIMERISM

Background. Development of donor-specific micro-chimerism (DSM) has be en proposed as one of the possible mechanisms for induction and mainte nance of allograft tolerance, The aim of this study was to determine: (1) the state of DSM in liver transplant (LTx) and renal transplant (R Tx) recipients, (2) whether the persistent presence of an allograft is a requirement for maintenance of chimerism, and (3) whether donor-spe cific blood transfusions (DST) facilitate chimerism development in RTx recipients and whether this correlates with allograft function, Metho ds, Qualitative and quantitative analysis of DSM in peripheral blood o f LTx and RTx recipients was assessed by polymerase chain reaction and competitive polymerase chain reaction using HLA-DR probes for mismatc hed antigens between the donor and recipient. Results, LTx recipients (11 of 12) who had or were having rejection were positive for DSM in c irculation compared with 4 of 11 with normal allograft function (P<0.0 1), The number of donor cells did not correlate with allograft functio n, LTx recipients (4 of 4) who lost their first allograft and underwen t retransplantation retained DSM for the first donors, RTx recipients who received DST (8 of 8) were positive for DSM compared with 6 of 12 of nontransfused recipients (P<0.045). Conclusions, The results sugges t that LTx and RTx recipients undergo rejection despite DSM, The devel opment of DSM may not be a prerequisite for normal allograft function, Once DSM is established, the presence of the allograft is not require d for maintenance of chimerism, DST facilitated the development of DSM in RTx recipients, Direct correlation was not observed between the de velopment of DSM and allograft function in either DST or nontransfused RTx recipients.