Researchers describe how specific gene activity could potentially enhance immune cell production. The researchers wanted to understand the mechanism of why some hematopoietic stem cells produce more immune cells, while other stem cells produce fewer. The research team pioneered new techniques for understanding the quantitative association between immune cell production and gene expression in lab mice. The scientists labeled individual stem cells with genetic ‘barcodes’ to track their immune cell production. They then correlated the barcode tracking with measurements of gene expression activity. They also developed innovative bioinformatics approaches to characterize their quantitative association. The scientists identified nearly 40 genes that are related to immune cell production. They discovered associations between the activity of these genes and both the quantity and variety of immune cells produced.