Kidney graft rejection studies with labeled platelets and lymphocytes.

The usefulness of In-111-labelled platelets and lymphocyte scintigraphy in acute kidney graft rejection is evaluated. One hundred fifty-five patients (36 treated with cyclosporine A) were studied with labelled platelets and 27 with labelled lymphocytes. Blood cels were labelled with 100-150 microCi of In-111-oxine and reinjected. Subsequently patients were scanned once daily from 2 hours post-reinjection up to a week. The graft/contralateral area activity ratio was calculated in all scans (index I). Four groups of patients were established: Functioning grafts (FG); post-operative acute renal failure (p-ARF); acute rejection (AR) and nephrotoxicity (NTX), the last one only in patients under cyclosporine therapy. Results with labelled platelets showed similar index I mean values in FG, p-ARF and NTX patients I = 1.1 +/- 0.1 and a significant increase (p less than 0.001), in acutely rejecting grafts I = 1.9 +/- 0.4. Evolving controls showed a decrease a decrease of graft activity parallel to rejection resolution while the activity maintains or increases in patients with less or no response to treatment. Overall sensitivity was 97.2%, specificity 90.2% and accuracy 92.8%. Results with labelled lymphocytes were similar to those with platelets. They showed a significant (p 0.001) difference of activity index between rejecting (I = 1.86 +/- 0.3) and non rejecting grafts (I = 1.05 +/- 0.1). Decrease of graft activity was only seen in patients with good response to treatment. It is concluded that In-111-labelled platelets scintigraphy is nowadays the method of choice for acute kidney graft rejection diagnosis, especially in patients under cyclosporine immunosuppression.