The crossmatch in renal transplantation.

Abstract

During the past 4 years, 60 renal transplants (out of a total of 191) have been performed in the presence of a positive crossmatch between recipient serum and donor lymphocytes, in a lymphocytotoxic assay. Forty‐five grafts had a positive B‐cell crossmatch and 15 had a positive T + B cell crossmatch. The results of these transplants at both 1 month and in the long term, as assessed by actuarial survival curves, are similar to those seen where the transplant was performed with a negative crossmatch.Of the 45 recipients with a positive B‐cell crossmatch, reactivity with autologous lymphocytes was tested in 30, and 14 proved to be positive. Their survival rate was higher than that seen in the B‐cell positive crossmatch transplants not due to autoreactive antibodies, although the difference was not statistically significant. Of the 15 recipients with a positive T + B cell crossmatch 13 proved to be due to autologous reactivity. Again the survival rate was higher than that seen in the negative crossmatch grafts.Two‐thirds of the positive crossmatch grafts were implanted into recipients with antibodies reacting with over 85% of random panel cells. These patients would be considered extremely difficult or impossible to transplant in units with a policy of transplanting only with a negative crossmatch.Overall, our results show that donor‐reactive B‐cell antibodies and T + B cell antibodies which are autoreactive are not associated with increased graft failure. However, we have noticed a relatively high non‐function rate in the positive crossmatch transplants (particularly B‐cell positive). This suggests that there is still considerable heterogeneity of the antibodies which may give rise to a B‐cell positive crossmatch, and although most of these antibodies are harmless, it does seem that some are damaging. Thus it is important to further characterize the specificities of these antibodies and determine their effect on a subsequent renal allograft.