Continuous monitoring of human kidney transplants by autologous labelled platelets

Indium-111-oxine labelled autologous platelets were prepared and injected in 75 renal transplant patients, who were collected in 3 groups of 25 persons each. Group 1 consisted of cases examined during the first 4 weeks after transplantation, group 2 of patients suffering from histologically proven chronic rejection and group 3 of cases with good and stable grafts a long time after transplantation. The grafts were monitored by gamma camera imaging and the calculation of a platelet-uptake index (PUI), as well as by estimation of platelet t/2. For diagnosis of acute rejection the platelet scan was of great help, when PUI rose from 1.13+-0.11 to 1.74+-0.17. The further outcome of graft rejection, reversible or irreversible, documented itself in a decrease or a sustaining high level of PUI respectively. The PUI of patients with chronic rejection differed significantly from those of cases with long-term stable grafts. The platelet t/2 correlated well with PUI. The possible pitfalls of this method giving a false positive result are haematomas and theoretically the recurrence of haemolytic-uraemic syndrome after transplantation. All in all the authors regard this method as an important and conclusive item in the rather complex mosaic of rejection diagnosis. (Auth.)