During vertebrate hematopoiesis many specialized cell types are formed
with vastly different functions such as B cells, T cells, granulocytes,
macrophages, erythrocytes and megakaryocytes. To tightly control the
enormous proliferative potential of developing blood cells, an
intricately balanced signaling and transcription network has evolved
that ensures that the different cell types are formed at the right time
and in the right numbers. Intricate regulatory mechanisms ensure that
blood cells function properly and have a determined life span. Moreover,
in the adaptive immune system, long-lived memory cells have evolved that
ensure that when pathogens have been seen once they will never cause a
problem again. In this book we will therefore make a journey from asking
how more primitive organisms use the epigenetic regulatory machinery to
balance growth with differentiation control towards digging deep into
what controls the function of specialized cells of the human immune
system. We will first discover that flies make blood but exist without
blood vessels, why fish make blood cells in the kidney and which precise
genetic circuitries are required for these developmental pathways. We
will then learn the regulatory principles that drive the differentiation
of mature blood cells from stem cells and what controls their function
in mammals. In the process, we will find out what unites hematopoietic
stem cells and endothelial cells. Finally, we will shed light on the
molecular mechanisms that either alter hematopoietic cell
differentiation or lead to the development of cells with impaired
function.
