Following antigen encounter, activated T cells can give rise to functionally distinct T cell subsets. Understanding how different T cell subsets arise requires technologies that can monitor the... Show moreFollowing antigen encounter, activated T cells can give rise to functionally distinct T cell subsets. Understanding how different T cell subsets arise requires technologies that can monitor the developmental potential of single precursor cells (chapter 2). This thesis describes the development and use of two novel genetic tagging strategies aimed at following cell differentiation in vivo. These strategies are based on the marking of precursor cells with unique DNA sequences (barcodes), following which cell fate is analyzed by barcode comparison of different daughter populations. The first technology, termed cellular barcoding, makes use of a retroviral barcode library to provide T cells with unique genetic tags via in vitro transduction. Cellular barcoding was used to analyze the kinship of diverse T cell populations (chapter 3-5) as well as to measure the clonality of antigen-specific T cell responses under varying conditions of infection (chapter 6). The second technology, termed in vivo barcoding, makes use of a transgenic mouse model in which unique DNA sequences are introduced via inducible VDJ recombination. The feasibility of in vivo barcoding was demonstrated by conditionally labeling lung and liver cells with different barcodes (chapter 7). Together, these studies have yielded important new insights for vaccine optimization. Show less
