THE CLINICAL-SIGNIFICANCE OF FLOW-CYTOMETRY CROSS-MATCHING IN HEART-TRANSPLANTATION

Background: Flow cytometry crossmatching is more sensitive than cytoto xic methods in identifying preformed antibodies to donor alloantigens. However, the significance of a positive flow crossmatch remains unkno wn for a recipient of a heart transplant who has a negative antihuman globulin crossmatch. Methods: Flow crossmatching was performed retrosp ectively for 92 recipients of a primary cardiac allograft who underwen t transplantation with a negative AHG crossmatch. Results: Forty-six p atients were flow crossmatch-positive for alloantibody: 20 were positi ve on both T and B lymphocytes, 12 were positive only on B lymphocytes , and 13 were positive only on T lymphocytes. Eleven had autoantibody invalidating the flow crossmatch with donor cells. Thirty-six patients had negative flow crossmatch, A significantly higher incidence of gra ft dysfunction with vascular rejection by 6 months was found for patie nts who had a positive flow crossmatch on B lymphocytes. This group al so had an increased incidence of mortality within this same period. Pa tients who were flow crossmatch-positive on T and B lymphocytes were m ore likely to experience greater than two episodes of treated cellular rejection within the first 6 months. Flow crossmatch-positive patient s stayed longer in the hospital in comparison to the other two groups, although the increases were not statistically significant. There were no differences between groups with regard to time to first rejection, absence of rejection episodes, episodes of decreased cardiac index (< 2.3 L/m(2)), depressed left and right ventricular ejection fraction, o r development of transplant atherosclerosis. Conclusion: A positive fl ow crossmatch identified a subset of patients who are predisposed to d evelopment of vascular rejection or are more likely to have frequent c ellular rejection.