Here we sought to determine physiologically active cell type-specific eQTLs of high relevance to immunity and inflammation in paired samples of monocytes and B-cells, freshly purified by positive selection. Our analysis highlights both the extent of eQTL cellular specificity, especially for trans-acting variants, and the underlying inherent complexity of eQTL action. We observe multiple examples of genes with eQTL in both cell types but to different loci, and of eQTL showing opposing cell-type dependent directional effects. Mapping genetic determinants of gene expression in these immune cell types is shown to be highly informative for reported GWAS hits, notably involving immune, infectious and inflammatory disease.
