Hematopoiesis Essay

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Severe Combined Immune Deficiency as described by the immune deficiency foundation, is a “cellular immunodeficiency and a potentially fatal primary immunodeficiency in which there is combined absence of T-lymphocyte and B-lymphocyte function” (Immune Deficiency Foundation IDF, 2016). The lymphatic system comprises of organs and tissue that produce immune cells and one of their main functions is to confer immunity to every part of the body. The function of the T-lymphocyte and B-lymphocyte in the lymphatic immune system cannot be overstressed as they make up the major responses that the immune system gives when it encounters a foreign antigen. Hematopoiesis is a process that involves the generation of most cells involved in immune reactions …show more content…
First, the pathogen, either intracellular or extracellular will come in contact with the first line of defense which usually involves the physical barriers, chemical barriers and genetic components of the host. This first line of defense involves non-specific, innate immunity and it can confer immunity to the host by preventing the pathogen from passing through the skin and the mucous membrane into the host cell. Some pathogens however bypass this line of defense and make it through to the second line of defense which is also a nonspecific defense but it involves the stimulation of other lymphocytes to respond. They also produce defensive proteins to combat these organisms. Members of the second line of defense include inflammation, phagocytosis, complements and macrophages. In cases where the second line of defense could also not attack and kill these pathogens, the third line of defense comes into play. This is a more specific defense mechanism that the body has to fight against pathogens that bypassed the first and second line of defense and it is only in cases where there is a disorder or a nonfictional defense system that the pathogen will overcome the host cell. In most cases of SCID, the third line of defense is usually defective mainly because the lymphocytes, antibodies and other cells involved in the third line of immune defense system like the natural killer cells are either low in number, nonfunctional or not present at all. The lines of defense are there an integral part of the diagnosis of SCID as they can be used to determine the blood count in an infected

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