What is polymorphonuclear leukocytes?

Polymorphonuclear leukocytes (PMNs), also known as polymorphs, polys or segs, are a type of white blood cell that plays a vital role in the body's immune system. They are the most abundant type of leukocyte, accounting for 60-70% of all circulating white blood cells.

PMNs are characterized by their multi-lobed nucleus, which gives them their name (poly = many, morph = shape, nuclear = nucleus). They are also highly motile and can rapidly migrate to sites of infection or injury.

PMNs play a critical role in both innate and adaptive immunity. In innate immunity, PMNs are involved in phagocytosis, the process by which foreign particles and microorganisms are engulfed and destroyed. They also release antimicrobial substances, such as reactive oxygen species and defensins, which help to kill and remove invading pathogens.

In adaptive immunity, PMNs help to activate other immune cells, such as T cells and B cells. They also produce cytokines, which are small proteins that regulate the immune response.

PMN counts can vary widely depending on a person's health status. In general, a normal PMN count is between 4,000 and 10,000 cells/µL. However, the PMN count can increase in response to infection or inflammation, and may also be decreased by certain conditions, such as chemotherapy.

A high PMN count may indicate an infection, inflammation, or tissue damage. A low PMN count may indicate bone marrow failure, an autoimmune disorder, or certain types of cancer.

If you have an abnormal PMN count, it is important to talk to your doctor to determine the cause and receive appropriate treatment.