THE CROSS-MATCH IN RENAL-TRANSPLANTATION - EVALUATION OF FLOW-CYTOMETRY AS A REPLACEMENT FOR STANDARD CYTOTOXICITY

Flow cytometry (FC) is increasingly being used as a crossmatch procedu re in addition to the standard complement-dependent cytotoxicity (CDC) test. In fact, FC offers a number of advantages over CDC and has the potential to become the primary crossmatch technique for cadaveric don or renal transplantation. We evaluated this possibility in 230 patient s crossmatched by both CDC and FC. The results showed that when the T cell crossmatch was negative by FC it was always negative by CDC, and that when the T cell results were positive by CDC (IgM antibodies excl uded) they were also positive by FC. As expected, a number of tests we re T cell-positive by FC but negative by CDC. AT cell CDC crossmatch w as more likely to be positive when FC was positive for both T and B ce lls and when FC results were quantitatively higher. However, FC was un able to consistently predict a positive, dithiothreitol-resistant B ce ll CDC crossmatch. A policy to transplant patients with negative FC re sults (70% of the patients evaluated) and not to transplant sensitized patients with FC+ T cell results (10%) would allow us to make a final decision with only FC in 80% of the cases. Actual graft survival was similar for nonsensitized first-transplant candidates with positive (8 3%) or all patients with negative (86%) FC results. We conclude that F C is sufficient to make a final decision in most cases. Wider utilizat ion will require improvements in the ability of FC to measure B cell a ntibodies and to quantitate antibodies to T cells.