Examples of granular leukocyte

Basophils are a type of white blood cell. Although they’re produced in the bone marrow, they’re found in many tissues throughout your body.

They’re part of your immune system and play a role in its proper function.

Whether you scrape yourself during a fall or develop an infection from a wound, you can count on your basophils help to get you healthy again.

In addition to fighting parasitic infections, basophils play a role in:

Preventing blood clotting: Basophils contain heparin. This is a naturally occurring blood-thinning substance.

Mediating allergic reactions: In allergic reactions, the immune system is exposed to an allergen. Basophils release histamine during allergic reactions. Basophils are also thought to play a role in causing the body to produce the antibody called immunoglobulin E (IgE).

This antibody then binds to basophils and a similar type of cell called mast cells. These cells release substances such as histamines and serotonin. They mediate the inflammatory response in the area of your body that was exposed to the allergen.

Neutrophils are a type of white blood cell. They make up the biggest number of all kinds of white blood cells. They kill and digest bacteria and fungi to help your body fight infections and heal wounds. 

White blood cells make up about 1% of your body's total blood cells and are an important part of your immune system. Neutrophils are the cells that respond first to any type of infection or wound. These make up 50% to 75% of your white blood cells. Neutrophils are made in your bone marrow. They live less than a day, so your bone marrow constantly makes new ones.

Normal neutrophil counts depend on different factors such as age — but generally, a low neutrophil level is less than 45% of your total white blood cells or 1,5000 neutrophils per microliter. A normal neutrophil level is between 1,500 and 8,000 neutrophils per microliter. A high neutrophil level is over 8,000 neutrophils per microliter. 

Eosinophils, sometimes called eosinophiles or, less commonly, acidophils, are a variety of white blood cells (WBCs) and one of the immune system components responsible for combating multicellular parasites and certain infections in vertebrates. Along with mast cells and basophils, they also control mechanisms associated with allergy and asthma. They are granulocytes that develop during hematopoiesis in the bone marrow before migrating into blood, after which they are terminally differentiated and do not multiply. They form about 2 to 3% of WBCs.

These cells are eosinophilic or "acid-loving" due to their large acidophilic cytoplasmic granules, which show their affinity for acids by their affinity to coal tar dyes: Normally transparent, it is this affinity that causes them to appear brick-red after staining with eosin, a red dye, using the Romanowsky method. The staining is concentrated in small granules within the cellular cytoplasm, which contain many chemical mediators, such as eosinophil peroxidase, ribonuclease (RNase), deoxyribonucleases (DNase), lipase, plasminogen, and major basic protein. These mediators are released by a process called degranulation following activation of the eosinophil, and are toxic to both parasite and host tissues.

In normal individuals, eosinophils make up about 1–3% of white blood cells, and are about 12–17 micrometres in size with bilobed nuclei. While they are released into the bloodstream as neutrophils, eosinophils reside in tissue. They are found in the medulla and the junction between the cortex and medulla of the thymus, and, in the lower gastrointestinal tract, ovaries, uterus, spleen, and lymph nodes, but not in the lungs, skin, esophagus, or some other internal organs under normal conditions. 

Following activation, eosinophils effector functions include production of the following:

Cationic granule proteins and their release by degranulation

Reactive oxygen species such as hypobromite, superoxide, and peroxide (hypobromous acid, which is preferentially produced by eosinophil peroxidase)

Lipid mediators like the eicosanoids from the leukotriene (e.g., LTC4, LTD4, LTE4) and prostaglandin (e.g., PGE2) families

Enzymes, such as elastase

Growth factors such as TGF beta, VEGF, and PDGF

Cytokines such as IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-13, and TNF alpha

There are also eosinophils that play a role in fighting viral infections, which is evident from the abundance of RNases they contain within their granules, and in fibrin removal during inflammation. Eosinophils, along with basophils and mast cells, are important mediators of allergic responses and asthma pathogenesis and are associated with disease severity. They also fight helminth (worm) colonization and may be slightly elevated in the presence of certain parasites. Eosinophils are also involved in many other biological processes, including postpubertal mammary gland development, oestrus cycling, allograft rejection and neoplasia.They have also been implicated in antigen presentation to T cells.

Eosinophils are responsible for tissue damage and inflammation in many diseases, including asthma.High levels of interleukin-5 has been observed to up regulate the expression of adhesion molecules, which then facilitate the adhesion of eosinophils to endothelial cells, thereby causing inflammation and tissue damage.

An accumulation of eosinophils in the nasal mucosa is considered a major diagnostic criterion for allergic rhinitis (nasal allergies).