Comparison of Complement-Dependent Cytotoxicity, Enzyme-Linked Immunosorbent Assay and Flow Cytometric Assay for the Detection of HLA Class I Alloantibodies

Ki, Chang Seok; Yang, Yun Sun; Kim, Dae Won

Abstract

BACKGROUND: To detect anti-HLA class I alloantibodies in potential solid organ recipients, panel reactive antibody (PRA) test using complement-dependent lymphocytotoxicity (CDC) has been widely utilized. Recently, enzyme-linked immunosorbent assay (ELISA) and flow cytometry based methods (Flow PRA) were developed. We have compared these three methods for the detection of anti-HLA class I alloantibodies.
METHODS
A total of 30 sera of various PRA reactivity determined using home-made CDC PRA panel were compared with ELISA PRA by QuikScreen Solid Phase HLA Antibody Screening Kit (GTI, Brookfield, USA). Among these samples, 19 sera were also compared with Flow PRA by FlowPRA I Screening Test (One Lambda, Inc., Canoga Park, USA). Qualitative as well as semiquantitative results using CDC %PRA, ELISA OD ratio (ratio of the test OD value divided by the x2 the value obtained for the mean of the negative controls) and Flow %PRA were compared.
RESULTS
Sixteen out of 19 sera (84%) showed concordant results among all three methods, and 11 sera tested by both CDC PRA and ELISA PRA but not by Flow PRA showed perfect concordance. CDC %PRA, ELISA OD ratio, and Flow %PRA showed excellent correlation between each other (Pearson's correlation coefficient >0.67, P<0.005).
CONCLUSIONS
Results obtained in this study indicate that ELISA PRA and Flow PRA tests might be good alternatives of conventional CDC PRA for the screening of anti-HLA class I alloantibodies in potential solid organ recipients.