QUANTITATIVE-ANALYSIS OF THE EXPRESSION OF THE HLA-DRB GENES AT THE TRANSCRIPTIONAL LEVEL BY COMPETITIVE POLYMERASE CHAIN-REACTION

In addition to polymorphism of the peptide-binding site, the density o f the MHC class II molecules expressed on the membrane of APC could we ll play a significant role in the MHC-peptide-TCR interaction during t he immune response, We therefore investigated the regulation of the ex pression of the HLA-DRB genes at the transcriptional level, A competit ive PCR approach was used to estimate the quantities of the HLA-DRB tr anscripts in peripheral blood B cells, When comparing the amounts of s teady-state mRNAs among the different DRB1 alleles, the DRB1 transcrip ts in the DR52 haplotype group were found to be 2.5 to 3.5 times more abundant than the DRB101 transcripts, 1.5 to 2 times more abundant th an the DRB104 transcripts, and 7 times more abundant than the DRB1*08 transcripts. Within the DR52 haplotype group, the DRB1 and DRB3 trans cripts had the same abundance, Taken together, these results are in go od agreement with the previously reported transcriptional activities o f the DRB promoters except for DRB104, thus suggesting a differential post-transcriptional regulation among the DRB1 mRNAs.