Neutrophils

• Neutrophils are the most common granulocyte, accounting for more than half of the total number of white blood cells. They have very short life spans, remaining in the blood for only about 12 hours. These cells work hard to perform phagocytosis, the engulfing of and destroying of debris and pathogens. After battling an infection, dead neutrophils are left behind in a pus that is a mixture of fluid and other cell parts. Neutrophils are essential to health, and a deficiency of them is considered life threatening.
  
  

Neutrophil Nicknames

• The neutrophil is known by many nicknames, based on what appearance it has and what it is doing at the time. Because the nucleus of a neutrophil can have so many different shapes and sizes, they are sometimes called polymorphonuclear leukocytes. "Seg" is the name for a mature neutrophil whose nucleus appears to have many lobes or to be segmented. Band cells are immature neutrophils with a nucleus that resembles a curved, thick band. These are sometimes called staff cells because the band resembles a staff.
  
  

Basophils

• Basophils are usually present in much smaller numbers than neutrophils. They account for less than 1 percent of the total white blood cells. They release histamine during a response to inflammation. They also release the anticoagulant heparin. Basophils are usually found in the lungs and the liver, where there is a large volume of blood, and it's possible that the heparin they release helps prevent tiny blood clots from forming.
  
  

Eosinophils

• Eosinophils make up 1 to 3 percent of leukocytes. Not a lot is known about them, but it is clear that they are involved in the body's response to inflammation. Eosinophils release chemicals that can destroy pathogens. A person who is in the midst of an allergic reaction will have an increased number of eosinophils in his bloodstream, as will a person who is fighting a parasitic infection.
  
  

Lymphocytes

• Lymphocytes make up between 25 and 38 percent of all leukocytes. Lymphocytes play a large role in the body's immune system. There are two subdivisions of lymphocytes, B-lymphocytes and T-lymphocytes. B-lymphocytes are created in the bone marrow, while T-lymphocytes are generated in the thymus gland. The main function of these cells is to create and release antibodies and to protect the body from cancer cells.
  
  

Monocytes

• Monocytes, like neutrophils, can perform phagocytosis. They account for 3 to 8 percent of all white blood cells, yet they are more efficient at destroying pathogens. These cells change into macrophages, which are able to leave the bloodstream and enter body tissue. Monocytes then patrol the body looking for pathogens and debris to clean up. Macrophages are common in the mucus membranes and under the skin, where they can be readily available to fight anything that invades the body through a small tear or scratch. These cells provide another service to the body as well: They phagocytose old red blood cells, helping the bloodstream remain healthy.