Error rate for HLA‐B antigen assignment by serology: implications for proficiency testing and utilization of DNA‐based typing methods

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Abstract
Until recently, the majority of HLA class I typing has been performed by serology. Expensive commercial typing trays are frequently used for testing non‐Caucasian subjects and new strategies using DNA‐based methods have been adopted for improving clinical histocompatibility testing results and adapted as supplements in proficiency testing. A double‐blind comparison of the typing of HLA‐B specificities in 40 samples was carried out between serology and two polymerase chain reaction (PCR) methods, PCR amplification with sequence‐specific primers (PCR‐SSP) and PCR amplification and subsequent hybridization with sequence‐specific oligonucleotide probes (PCR‐SSOP). The results demonstrated 22.5% misassignments of HLA‐B antigens by serology. There was complete concordance between the results obtained with the two PCR based typing methods. A second panel of 20 donor samples with incomplete or ambiguous serologic results was analyzed by PCR‐SSP and SSOP. Both PCR methods identified correctly the HLA‐B antigens. Our results suggest that more accurate typing results can be achieved by complementing serologic testing with DNA‐based typing techniques. The level of resolution for HLA‐B antigen assignment can be obtained by this combination of serology and limited DNA‐based typing is equivalent to the HLA‐B specificities defined by the WHO‐HLA Committee. This level of resolution cannot routinely be achieved in clinical histocompatibility testing or in proficiency testing using serologic reagents only.