Haematopoiesis in the steady-state is reasonably well understood. However, upon emergency situations such as infection or inflammation, homeostasis is broken and cell numbers can rise substantially e.g. neutrophil numbers after infection with Listeria monocytogenes. What is not currently clear is whether this is due to the same progenitors producing more of a given cell type, or instead if there is recruitment of 'emergency' progenitors for this purpose. Cellular barcoding is a novel technology that can track the output of single stem and progenitor cells. Here, cells are transduced with lentivirus where each particle has a different DNA 'barcode' that is integrated into the genome, and thus inherited by daughter cells. By establishing the barcode signatures in progeny cell types in steady-state vs inflammatory conditions I aim to assess progenitor fate on the single cell level that gives rise to higher cell numbers. In my model I will be assessing the affect of G-CSF and flt3 ligand on the output of several immune cell types.