leukocyte kinetics & function

mitotic pool

cells capable of cell division in BM. myeloblasts, promyelocytes, myelocytes. all can divide (proliferate) and mature (differentiate). all are housed in the bone marrow. requires approximately 4 days (3-6) to progress from myeloblasts to metamyelocytes (post-mitotic).

post-mitotic & storage pool

differentiation without proliferation. metamyelocytes, bands, segmented neutrophils. none can divide, in BM. require 6-10 days to mature in BM prior to release into circulation. segs & bands released into circulation, many are retained/stored in BM.

circulating pool in peripheral blood

bands & segs (half released from BM). segs circulate 6-10 hours before immigrating into tissue.

marginating pool in peripheral blood

half of segs released from bone marrow. can move from this pool to the other by stress or epinephrine. can also move out of blood in response to infection

WBCs in tissues

segs enter tissue randomly unless chemotactically attracted by infection. segs live 3-5 days in tissue, die, and don’t re-enter circulation. primary function is to combat bacterial infections through phagocytosis