Definition

• Leukocytes or white blood cells are components of the blood that help protect your body against infections, virus, bacteria, parasites, tumors and dead cells.
  
  

Neutrophils

• The neutrophil, according to the American Society of Hematology, "accounts for 55-70 percent of the total leukocytes and lives less than a day". Thus, your body continuously generates neutrophils to maintain protection against foreign particles. Furthermore, these leukocytes are active 'bacteria-engulfers' at sites of infections such as in pus of wounds.
  
  

Eosinophils

• The eosinophils make up 2 to 5 percent of your total leukocyte count. These leukocytes increase in number during parasitic infections such as chronic diarrhea induced by helminths (intestinal worms).
  
  

Basophils

• The basophils, like the eosinophils, normally occur at low amounts in your blood and increases rapidly during infection. These leukocytes release "mediators" including histamine, prostaglandins and serotonin that plays an important role in hypersensitivity reactions. For instance, the basophils react to airborne allergens such as dust by releasing histamine, which in turn causes allergic rhinitis (hay fever).
  
  

Lymphocytes

• The lymphocytes are of two kinds; namely, B lymphocytes and T lymphocytes. These lymphocytes work in an organized manner. First, the T lymphocytes capture the bacteria in your cells and then the B lymphocytes create antibodies, which fight and help remove the bacteria. The same pattern occurs when lymphocytes try to protect your body against viruses.
  
  

Monocytes

• The monocytes are the largest type of leukocytes. These large leukocytes act as "macrophages" that engulf germs and dead cells, which the neutrophils and other leukocyte groups can't effectively eliminate.