Allele-specific quantification of HLA-DQB1 gene expression by real-time reverse transcriptase-polymerase chain...

In addition to coding region polymorphism, allele-specific variation in the upstream regulatory region of the HLA-DQB1 gene has been detected. Reporter gene assays and transfection studies have indicated that HLA-DQB1 promoter polymorphism may be of functional significance. The aim of this study was to utilize real-time reverse transcriptase-polymerase chain reaction (RT-PCR) for allele-specific quantification of HLA-DQB1 expression and to analyze cell-specific HLA-DQB1 expression in vivo. For the allele-specific quantification of DQB1 gene products, a real-time RT-PCR set of primer pairs (n=27) and probes (n=5) targeting exon 2 variability was established. The robustness and integrity of the assay system were confirmed by using recombinant DQB1 exon 2 plasmid clones as active exogenous controls. Sensitivity and reproducibility were assessed by serial dilution and allelic mixing analyses. In application to the study of allele-specific expression of DQB1 gene products during cytokine-driven maturation of monocyte-derived dendritic cells, differential patterns of allelic expression in heterozygous individuals were observed for DQB1*0301, compared to DQB1*0501 and DQB1*0602. At maximum, 1.9-fold (*0301/*0501) and 2.5-fold (*0301/*0602) higher induction was seen for DQB*0301. In conclusion, HLA-DQB1 expression can be analyzed by real-time RT-PCR suitable for cell- and allele-specific detection of HLA-DQB1 transcripts in homo- and heterozygous combinations.