Types of WBCs
1) Neutrophils - most quickly of WBCs to tissue destruction by bacteria. After engulfing a pathogen by phagocytosis, it releases several chemicals to destroy it. 2) Lymphocytes - the major soldiers of an immune response. They continually patrol among lymphoid tissues, lymph fluid and blood.
There are 3 main types :
B Cells : particularly effective at destroying bacteria, and inactivating their toxins T Cells : attack viruses, fungi, transplanted cells, cancer cells, and some bacteria. They are responsible for transfusion reactions, allergies, and the rejection of transplanted organs Natural Killer Cells (NK Cells): attack a wide variety of infectious microbes and certain spontaneously arising tumors. 3) Monocytes - much longer to reach the site of infection but arrive in larger numbers and therefore more microbes destroyed. Upon their arrival, monocytes enlarge and differentiate into macrophages, which clean up cellular debris and microbes by phagocytosis after an infection. 4) Eosinophils - believed to release enzymes, such as histaminase, that combat the effects of histamine and other substances of inflammation. 5) Basophils - release granules that contain heparin, histamine, serotonin which intensify the inflammation reaction. Once granular leukocytes and monocytes leave the bloodstream to fight injury or infection, they never return. Lymphocytes, however, continually recirculate from blood to interstitial spaces of tissues to lymphatic fluid and back to blood. ~ 2% of the total lymphocyte population is circulating in the blood at any given time; the rest are in lymphatic fluid and organs such as skin, lungs, lymph nodes and spleen.
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