Background: A pretransplant positive cross-match is a contraindication for kidney transplantation, unlike combined liver and kidney transplantation (LKT). It is hypothesized that liver can protect kidney from rejection due to several tolerance inducing mechanisms.
Aim: To know the meaning of specific and non specific donor anti-HLA antibodies (HLAa) in LKT recipients after measuring periodically Mean Intensity of serum Immunofluorescence (MFI).
Methodology: MFI Class I and II HLAa were measured each three months in 12 recipients of LKT in a single center study. The mean follow-up was 6 years. We study the influence of positive HLAa on both graft and patient survival, kidney function, antibody mediated acute and chronic rejection comparing with a control group of 51 children in the same center with isolated kidney transplantation and positive HLAa.
Results: 66% of LKT recipients had positive MFI HLAa; 14% were of class I; 36% of class II and 7% of class I and II. According to HLA DQ antigens were not available in all donors, we only confirmed  donor specificity in two recipients. The highest level of MFI HLAa tittre  was 10 months after transplantation for class I (17000 MFI) and 53 months for class II (211304 MFI). Survival of the graft at 10 years was 100% in LKT and positive HLAa versus 64% in 51 isolated kidney transplant recipients and positive HLAa. Furthermore, glomerular filtration rate was significantly better in LKT recipients group: 86 versus 71 ml / min / 1.73 m2. There was no rejection in LKT recipients compared to 36% in isolated kidney recipients andthe positive HLAa.
Conclusion: Positive HLAa are frequent after LKT but this fact does not have bad prognosis and it could probably have a different meaning that the isolated renal transplant. Patients with a LKT and positive HLAa  have less risk of rejection, graft loss and better long-term renal function.