In addition, thanks to similar genetic engineering manipulations, an increasing number of factors that stimulate the production of other cells in the blood besides the red cells also are being brought into use. These include the all-important cells that regulate the immune system enabling the body to fight off infectious invaders. A wide variety of clinical studies are under way to explore the potential of these agents to improve the management of patients receiving anti-cancer drugs, many of which depress the cells of the immune system. Possible risks with the use of the agents also have to be evaluated. Hematopoietic growth factors orchestrate the blood-forming machinery of the body.
All blood cells develop from a parent cell in the bone marrow.
This process is controlled by growth factors, which play a role in the differentiation and production of certain blood cells, and in the activation of immune system cells in response to infectious agents. A number of potential human hematopoietic growth factors have been identified. The genes that provide the instructions to make the factors have been isolated and inserted into cells that can produce the hormone in quantity. Three of the principal types of white cells are granulocytes, monocytes and lymphocytes. Many leukemia patients have low levels of granulocytes.