Detection of HLA class I- and class II-specific antibodies by flow cytometry and PRA-STAT screening in renal transplant recipients.

Abstract

Screening for HLA-specific antibodies has been performed by complement-dependent lymphocytotoxicity for many years. In recent years, methods involving the use of flow cytometry or ELISA have been developed. This study has compared a flow cytometric screening technique for the detection of HLA class I- and class II-specific antibodies with a commercially available ELISA technique, PRA-STAT. A significant correlation was found between the two methods for the detection of antibodies in patients after transplantation (P<0.001). Specificity analysis confirmed that the PRA-STAT technique detected both HLA class I- and class II-specific antibodies. Screening of serum samples from patients who experienced graft loss by cytotoxic, flow cytometric, and PRA-STAT techniques showed that there was a significant correlation between all three methods for the detection of antibody, but that the best correlation for the panel-reactive antibody level was that between the flow cytometric and PRA-STAT techniques (r=0.86). This was principally due to the detection of both HLA class I- and class II-specific antibodies by these methods, whereas cytotoxic screening detected only class I-specific antibodies. These results suggest that PRA-STAT is a useful technique for the detection of both HLA class I- and class II-specific antibodies, rather than only class I-specific antibodies as previously described.