Clinical relevance of anti-HLA antibodies pre and post transplant

Pretransplant histocompatibility testing seeks to select compatible donor-recipient pairs for transplantation. Sera from prospective renal transplant recipients are screened for the presence of human leukocyte antigen (HLA) antibodies to determine humoral alloimmunization. Present techniques screen patient sera using a complement-dependent cytotoxicity assay and express the results as percent of panel reactive antibody (PRA). However, the standard assay suffers because it needs viable target cells, a variable sensitivity of cells for complement, subjective evaluation, a lack of standardized methodology, and a variable correlation with clinical outcomes. Alternatively, an enzyme-linked immunosorbent assay (ELISA) methodology can detect IgG anti-HLA reactivity based on the binding of immunoglobulin to soluble HLA class I antigens. This method provides increased objectivity and reproducibility, does not require use of viable target cells, and most importantly, detects immunoglobulin that is reactive to HLA class I antigens. Data discussed herein suggest that identifying reactive recipient sera using the enzyme-linked immunosorbent assay (ELISA) (PRA-STAT, Sang Stat Med, Menlo Park, CA) methodology may be more informative clinically than current standard percent of panel reactive antibody (PRA) assays.