INFLUENCE OF PRETRANSPLANT IGG AND IGA ANTI-HLA ANTIBODIES BY ELISA ON LIVER TRANSPLANT OUTCOME

INFLUENCE OF PRETRANSPLANT IGG AND IGA ANTI-HLA ANTIBODIES BY ELISA ON LIVER TRANSPLANT OUTCOME.
F Monteiro¹, H Rodrigues¹, C Viggiani¹ P Massarolo², Regina Leitão², Sérgio Mies², Silvano Raia² & Jorge Kalil¹.¹Laboratory of Transplantation Immunology and ²Liver Unity, School of Medicine, University of São Paulo - São Paulo, Brazil.

Although the presence of preformed antibodies (allosensitization) is a major risk factor influencing kidney graft survival, the effect of pretransplant sensitization on the outcome of liver transplant has been controversial.
To address its clinical significance, a retrospective analysis of 141 consecutive liver allograft recipients who underwent transplantation between Jul/1993 and Oct/1997 was performed by ELISA technique (PRA-STAT).For IgA isotype, the assay procedure was modified using IgA isotype peroxidase-conjugated antibody. For all assays, a ELISA %PRA value greater than 10% was considered positive. All patients had a minimum 12-month follow-up time. The immunossupression used was classical triple therapy: CSA+Pred+AZA and the diagnosis of rejection was biopsy proven. The correlation of pretransplant IgG ELISA %PRA and graft loss demonstrated that 23/128 patients (18%) with pretransplant PRA < 10% lost their graft, in contrast to 9/12 patients (75%) with pretransplant PRA > 10% (P< 0.0001). IgG ELISA results obtained using pretransplant sera also correlated with patient survival (P< 0.0001). Three fourths of patients (75%) who tested positive deceased, within the study period, compared with only 15% of patients who tested negative.
Regarding IgA ELISA %PRA results, only 7/116 patients (6%) studied for this isotype had IgA anti-HLA antibodies in the pre-transplant sera detected by ELISA. Our results showed the incidence of acute rejection as well as graft loss or patient survival was not significantly different between the positive and negative IgA %PRA groups.
In summary, these results suggest that pretransplant detection of IgG anti-HLA antibodies by ELISA identifies high-risk patients for graft loss. On the other hand, the presence of IgA anti-HLA antibodies is not harmful to liver allografts.