Myeloid compartments and maturation arrest

The absolute neutrophil count (ANC) determined from a standard CBC is only representative of the 5 percent of PMN in the vascular compartment (pink shading). The majority of functional PMN (bands and mature PMN, representing approximately 51 percent of total developing PMN) are in the maturation/storage pool in the bone marrow. In patients with an early myeloid arrest, the bone marrow reserve is depleted and there are no functional PMN available for delivery to the tissues. In contrast, when neutropenia occurs in the setting of late myeloid arrest or no arrest, mature PMN generally are available for fighting infection.