PMN

PMN or Polymorphonuclear leukocytes are a type of white blood cell distinguished by the presence of granules in their cytoplasm. They are also known as granulocytes and include neutrophils, eosinophils, and basophils. PMNs play a crucial role in the immune system's defense against infections.

Structure

PMNs are characterized by the presence of granules in their cytoplasm. These granules contain enzymes and other substances that help the cell to destroy bacteria and other pathogens. The nucleus of a PMN is divided into several lobes, which gives the cell its characteristic "polymorphonuclear" appearance.

Function

PMNs are part of the body's innate immune system. They are among the first cells to arrive at the site of an infection, where they engulf and destroy bacteria and other pathogens. PMNs also play a role in inflammation and the immune response to allergens.

Types of PMNs

There are three types of PMNs: neutrophils, eosinophils, and basophils. Each type has a different function in the immune system.

• Neutrophils are the most common type of PMN. They are highly effective at killing bacteria and are the primary cell type involved in acute inflammation.
• Eosinophils play a role in the immune response to parasites and allergens. They also contribute to tissue damage in certain diseases, such as asthma.
• Basophils are the least common type of PMN. They release histamine and other substances that promote inflammation.

Clinical significance

Abnormalities in the number or function of PMNs can lead to disease. For example, a low number of neutrophils (neutropenia) can make a person more susceptible to bacterial infections. On the other hand, an excessive number of eosinophils (eosinophilia) can cause tissue damage and inflammation in conditions such as asthma and allergic reactions.

See also

• White blood cell
• Immune system
• Inflammation

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