White Blood cells or WBC’s are known for their immunity building role in our body. Leukotrienes are one of the defense weapons of white blood cells which are lipids and play a pivotal role in immunity increasing function. They can also be expressed as the hormones which cause symptoms in asthma and hay fever (allergic rhinitis). They are responsible for activating many different types of white blood cells so as to fight the foreign material/organism invasion in our body. Biologists have found out that malfunctioning of Leukotrienes can result in aggravation of asthma and other diseases too.
Leukotrienes are eicosanoids which means they are a collection of oxygen derivatives of some 20 different essential fatty acids. The other eicosanoids are prostaglandins, prostacyclins and thromboxanes. Leukotrienes are produced along with the release of histamine. Leuko trienes are one class of eicosanoids lipid mediators which means they are signalling molecuels which occur by the oxidation of essential fatty acids at the site of inflammation or where immunity is required. These are derived from omega-3 fatty acids or the omega-6 fatty acids. There is no storage for leukotrienes as they have to be synthesized wherever they are required.
Various enzymes catalyze different chemical reactions in a series to enable the generation of Leukotrienes from arachidonic acid through a typical type of white blood cells – Leukocytes. Also it has been found that some times other intermediate products are used by different types of cells from the leukotriene pathway to convert them into thriving Leukotrienes biologically.
The different types of Leukotrienes range from the letters A to E and are differentiated on the basis of their functions and chemical structures. Leukotriene A does not react with any tissues but is considered as the precursor for all different leukotrienes whereas Leukotriene B is known to activate and attract cytokines (immune cells). Leutokrienes C, D and E are segmented as cysteinyl leukotrienes. As mentioned in the paper "The New England Journal of Medicine,"submitted in November 2007 by to Dr. Marc Peters-Golden and Dr. William Henderson Jr., Leukotriene D is the most influential amongst all leukotrienes in causing asthma by constricting air passages.
There is a specialized cell receptor present in the cell membrane. These defense system cells of white blood cells bind to them to trigger off a series of activities giving rise to cell movement and regulation of read-out genes. The cysteinyl leukotrienes have been found binding effectively to CysLT1 or CysLT2 receptors and the controlling of airways is influenced by CysLT1 receptors. CysLT2 receptors react to the inflammatory response and perform the function of regulating substances inside and outside of the blood. BLT1 receptors are strongly bounded by Leukotriene B thereby influencing the cytokines. Till date, the function of BLT2 receptors is not known.
Different Leukotrines affect the body in various ways. Cysteinyl Leukotrienes are known to cause smooth muscle contraction in the airways thereby constricting them. Neutrophils which are a type of white blood cells are attracted by the Leukotriene B resulting in captivation of bacteria and other foreign invaders. These two types of Leukotrienes are known to act as the main trigger for eruption of allergic reactions and they also make the leukocytes penetrate the tissue by leaving the main blood stream.
Some of the regular diseases triggered off by Leukotrienes are asthma, allergies, atherosclerosis, fibrotic disease, and certain cancers, inflammatory diseases such as psoriasis, lupus and arthritis. Leukotrienes show a special connection with the cancer cells as they have the enzymes in necessary level to produce leukotrienes and which help them increase their survival and proliferation. Drs. Peter-Golden and Henderson have pointed different evidences for explaining the fact that leukotrienes by over expression shows a correlation with stroke and heart attack rates in specific communities. According to stroke Merck Manual Leukotrienes cause coronary spasms by constricting blood vessels.
Food and Drug Administration (FDA) has given approval for the use of three drugs that can be used in treating asthma. To block the cysteinyl Leukotrienes action Montelukast and zafirlukast antagonize CysLT1 receptors are recommended while zileuton is known to restrict enzyme which is responsible for producing leukotriene B and cysteinyl leukotrienes.