CLINICAL SIGNIFICANCE OF SKIN CROSSMATCH IN KIDNEY TRANSPLANTATION.
J. Kalil1,4 ,R. A Silva1.; H.Rodrigues1.; Z. N. P Oliveira3. I. M. L.Fukumori3.; L. E. Ianhez2 W.Nahas2 & N. Panajotopoulos1.1Transplantation Immunology Laboratory - Heart Institute, 2Renal Transplantation Unit - Urology, 3Department of Dermatology, 4Department of Medicine, Division of Allergy and Clinical Immunology. Faculty of Medicine, University of Sao Paulo, Sao Paulo, Brazil.
It has been claimed that a positive skin crossmatch (XM), based on immunofluorescence staining of donor skin with recipient serum, predicts early kidney allograft rejection despite the presence of negative XMs by the most sensitive techniques. In order to define the incidence and clinical significance of positive skin XM, we have performed this test in 54 patients transplanted with kidneys from living related (LRD n.42), living unrelated (LURD n 4) and cadavers (CAD n.8) donors. Thirty nine of them were first grafts and 15 regrafts (RTX). T and B cell crossmatches were negative, even with the AHG protocol. Six patients resulted positive for donor skin XM (4 first and 2 RTX) and 3 of them (all with LRD) had early allograft failure while only 4 of 48 with negative skin XM lost the kidney during the 6 months after transplantation (p= 0.02). Of 15 RTX, 2 resulted positive for skin XM and lost the kidney during the first 2 months, and 13 negative with only one graft loss due to technical failure (p= 0.02). Four out of 39 patients with first graft presented positive skin XM ( one graft failure ) and 35 negative XM ( 3 graft failures). In order to better characterize these alloantibodies, we examined retrospectively XM after serum absorption on platelets. We determined antibodies specificity as non-HLA (platelet unabsorbed) in 4 cases studied so far (2 with kidney loss). In 2 additional cases (CAD. Regrafts), we detected by screening against a 10 skin panel, patient sensitization of 0% and 100 % respectively. The 100% reactivity was caused by anti-HLA class1 antibodies (lymphocyte PRA was 90%) and disappeared after serum absorption on platelets, i.e. no sensitization against skin was detected. The course of the 2 transplants is excellent until now, 12 months after transplantation. In conclusion, it appears that positive skin XM is not a rare event and, at least in our study, it was accurate in predicting early allograft failure in recipients who had previously rejected a kidney allograft.