The Essential Role of Neutrophils in Immune Defense
Neutrophils are vital immune cells responsible for battling bacterial infections and playing a significant role in immune response and autoimmune diseases. They originate in the bone marrow and make up a significant portion of white blood cells. Understanding their functions and causes of low levels is crucial for managing infections and autoimmune conditions effectively.
The Vital Function of Neutrophils in Immunity
Neutrophils: Key Players in Our Immune System
Over millennia, multicellular life forms have evolved mechanisms to combat pathogens, with neutrophils standing out as crucial defenders. These specialized phagocytes engulf and eliminate bacteria, although they are less effective against viruses. Present primarily in higher animals, neutrophils constitute 50% to 70% of white blood cells, forming the backbone of immune defenses.
What Are Neutrophils?
Produced in the bone marrow's soft, trabecular tissue located within long bones and pelvic bones.
Bone marrow generates neutrophils from abundant stem cells.
Alongside basophils and eosinophils, they are polymorphonuclear cells with lobed nuclei.
The name 'neutrophil' derives from their neutral pink staining characteristics.
Approximately 50-60% of marrow activity focuses on producing these cells.
Normal circulating neutrophil levels range from 40% to 70% of white blood cells.
Understanding Neutropenia – Low Neutrophil Count
Various medical conditions can cause decreased neutrophil levels, a condition known as neutropenia.
Causes range from congenital issues and infections to treatments and systemic illnesses.
Causes of Neutropenia
Genetic disorders such as Kostmann’s syndrome and myelokathexis.
Medical therapies like chemotherapy and radiation therapy.
Infections including tuberculosis, hepatitis, HIV/AIDS, and malaria.
Severe infections like sepsis can deplete neutrophil reserves.
Conditions like leukemia, hypersplenism, autoimmune diseases, and certain drugs can also diminish neutrophil levels.
Neutrophils in Action – Their Defense Functions
Primarily tasked with fighting bacterial infections.
They migrate from blood vessels to infected tissues through a process called chemotaxis.
Their motility is rapid; pseudopodia formations enable movement towards infection sites.
Recent studies reveal a coordinated process called neutrophil swarming, enhancing immune response.
How Neutrophils Eliminate Pathogens
Pseudopodia surround and engulf bacteria, releasing destructive chemicals to kill them.
They form neutrophil extracellular traps (NETs), which consist of chromatin and antimicrobial substances, trapping and killing bacteria extracellularly.
Neutrophils and Autoimmune Disease
Their role in tissue damage is well-known, especially in autoimmune conditions.
Recent research suggests neutrophils promote inflammation and contribute to lesion development, for example, in atherosclerosis.
Neutrophils are now recognized as sources of autoantigens, implicating them further in autoimmune pathogenesis.
