White Blood Cells and What Are They

White Blood cells, or 'leukocytes' are the cells that help you fight off diseases. They are found in the immune system. There are different kinds, but they are all come from a multipotent cell, which are found in the bone marrow known as 'lymphatic system'.

The number of white blood cells in the blood can show if there is a disease present. It cannot tell what disease. To 1 liter of blood, there is normally 4×109 and 11×109 white blood cells, which make up about 1% of
the blood in an average adult.

Types

The different straining granules in their cytoplasm when seen under a microscope know granulocytes white blood cells. These granules are membrane-bound enzymes that mainly act in the digestion of endocytosed particles. There are 3 types of these. Europhiles, basophils, eosinphils. They are named after the straining properties.

Neutrophil

Neutrophils guard against bacterial or fungal infection and they are usually first responders to microbial infection; their activity and death in large numbers forms pus. They are also known as polymorphonuclear whit blood cells. They have a multilobed nucleus, which may appear like multiple nuclei. The cytoplasm look transparent because of fine granules that is faintly pink in color. Neutrophils are very active in phagocytosing bacteria and are present in the pus of wounds. These cells do not renew their lysosomes used in digesting microbes and die after having phagocytosed a few pathogens.

Eosinophil

Eosinophils mainly deal with parasitic infections and an increase in them may indicate such. Eosinophils are also the main inflammatory cells in allergic reactions. The most important causes of eosinophilia include allergies such as asthma, hay fever, and hives and parasitic infections. Usually their nucleus is bi-lobed. The cytoplasm is full of granules, which gets a pink-orange color with eosin stain.

Basophil

Basophils are mainly responsible for allergic and antigen response by releasing the chemical histamine causing inflammation. The nucleus is bi- or tri-lobed, but it is hard to see because of the number of coarse granules, which hide it. They are known by their large blue granules.

Monocyte

Monocytes share the "vacuum cleaner" function of neutrophils, but are much longer lived as they have an added role: they give pieces of pathogens to T cells so that the pathogens may be recognized again and killed, or so that antibody response may be mounted. Monocytes slowly leave the
bloodstream to become tissue macrophages that take out dead cell as well as attacking microrganisms. Neither of these can be dealt with effectively by the neutrophils. Unlike neutrophils, monocytes are able to replace their lysosomal contents and thought to have a longer active life. They have the kidney shaped nucleus and typically agranulated. They also possess lots of cytoplasm.