White blood cells are known to people in general, but people aren’t aware of it in detail. White blood cells’, also known as leukocytes’ overall function is to protect body against any injury or disease, which make white blood cells an important component of body’s immune system.

There are three different types of granulocytes: neutrophils, Eosinophils and Basophils. Neutrophils are the most abundant white blood cells in our body. Their main function is to kill any foreign molecules, thus they are the first responders to any invasion of bacteria. They maintain our body’s health through phagocyting, engulfing the bacteria. Eosinophils fight with the infection of parasitic worms. They kill those worms through releasing toxins and aid with the immflamatory response when an allergic reaction occurs. Basophils produce two chemicals: histamine and heparin. Histamines are also involved in allergic reaction and heparin is an anticoagulant. Anticoagulants are responsible for aiding the clotting of an injured part of the body, which allows more blood to flow to the region, thus enhancing the healing.

There are two different types of agranulocytes: Monocytes and lymphocytes. Monocytes are the largest amoung the white blood cells and they are the cells that tidy up the blood the most. They employ phagocytosis to engulf foreign particles, kill and break down those foreign particles using enzymes. Moreover, they assist other white blood cells to identify the types of germs that have invaded the body. Furthermore, they mend damaged tissues in our body through removing dead cells from the site, which allows the repairing of the wounds. It has been also seen that monocytes are also involved in the formation of particular organs such as heart and brain as a component holding tissues together. They even produce cytokines that aid the communication between other white blood cells. Lymphocytes are divided into 3 different cells: B cells, T cells and Natural Killer cells. B cells’ main function is to create specific antibodies for the specific antigens. T cells’ main function is involved with cell-mediated immunity. Cytotoxic T cells directly kill the cell containing the antigen through binding to them and burst open. Helper T cells activate other T cells and precipitate the production of antibodies produced by B cells. Regulatory T cells suppress B cells’ and other T cells’ response to antigens. Natural Killer cells have similar function with T cells, except the fact that they respond non-specifically to antigens. They attach to any cells they make contact with and if the cell triggers more of the Natural Killer cell’s activator receptors, Natural Killer cells cause the target cell to burst. If Natural Killer cell’s inhibitor receptors are more triggered by the attached cell, the Natural Killer cell will identify it as a normal cell and leave the cell.

Resources: http://biology.about.com/od/cellbiology/ss/lymphocytes.htm