Neutrophils have a relatively short life span. They are produced in the bone marrow, and when they reach the band or segmented stages are released into the peripheral blood. They remain there for approximately ten hours before randomly entering body tissues.
Neutrophils in the bloodstream can be divided into the circulating granulocyte pool (CGP) and marginating granulocytic pool (MGP). The white blood cell count reflects the cells in the circulating pool. The cells in the marginating pool move quickly into the circulating pool when needed.
During an infection, the neutrophil concentration of the peripheral blood can increase almost immediately due to the shift of these cells from the marginating pool and release from the bone marrow storage pool, if needed. Neutrophils then migrate to areas of tissue damage or infection. Neutrophils do not reenter the bloodstream from the tissues, thus ending their life in the tissues either due to phagocytosis or senescence.
