Finally, we demonstrate for the first time the possession of specific HLA alleles regulates gene expression in trans in a cell specific manner. The monocyte specific trans association of AOAH and ARHGAP24 expression to the possession of DRB1*04 , *07 and *09 alleles is particularly intriguing. Only these DRB1 alleles are associated with expression of HLA-DRB4, encoding the DR53 superantigen58. The reduced expression of AOAH, an enzyme that hydrolyses the potent innate immune stimulant lipopolysaccharide, in monocytes might be anticipated to pre-dispose towards inflammation. Whether the further association of ARHGAP24, encoding a protein involved in actin remodelling59, a requirement for monocyte spreading and locomotion60 is secondary to reduced AOAH expression will require further investigation. This study demonstrates that healthy individuals possess cell specific expression signatures attributable to HLA allele carriage, reflecting the overwhelming importance HLA status plays upon everyday immune interactions.
