Impaired renal graft survival after a positive B-cell flow-cytometry crossmatch

Background. The clinical and immunological relevance of a positive B-cell flow-cytometry (B-FCXM) crossmatch in renal transplantation is still controversial. Methods. We retrospectively analysed 145 consecutive cadaveric renal transplantations performed from May 1991 to September 1995 in our institution. All grafts were transplanted following a negative IgG T-cell complement-dependent cytotoxicity crossmatch (T-CDCXM). Concomitantly to CDCXM, B-cell and T-cell FCXM were performed and results were expressed as a mean fluorescence index (FI). Two groups were compared: 116 recipients grafted with a negative B-FCXM vs a group of 19 patients grafted with a positive B-FCXM. Results. The two groups were similar for length of cold ischaemia, donor and recipient's age and degree of HLA mismatching. The proportion of patients with pre-transplant anti-HLA class I antibodies or a retransplantation was significantly increased in the positive B-FCXM group vs the negative B-FCXM group. Recipient survival at 48 months was not significantly different in the two groups. However, graft survival at 12 and 48 months was significantly poorer in the positive B-FCXM than in negative B-FCXM (68% us 90% at 12 months: P=0.007, and 57% vs 79% at 48 months: P=0.02). Within the positive B-FCXM group, no differences were found in pre-transplant anti-HLA class I or II alloimmunization as well as retransplantation frequency between the patients who lost their graft and the patients who did not. Conclusion. Our results suggest that a pretransplant positive B-FCXM is associated with an impaired longterm graft survival in renal allotransplantation.