Hypersensitivity Reaction Essay Example | Topics and Well Written Essays - 1250 words

Hypersensitivity Reaction - Essay Example Hypersensitivity Reaction This paper aims to review the immunological mechanisms giving rise to the four groups of hypersensitivity. It also compares and contrasts hypersensitivity reactions caused by antibodies and those caused by T-lymphocytes, while also discussing the clinical consequences of each of the reactions using examples. Hypersensitivity reactions can be divided into type I-IV, based on the various involved mechanisms. Type I, often associated with allergy, is mediated by IgE. IgE triggers basophil and mast cell degranulation cross linking with antigen. Type II occurs on binding of the host’s cells to antigens, which marks them for destruction (Phillips, 2006 p89). Mediation is by IgG and IgM antibodies. Type III hypersensitivity triggering occurs due to aggregates of IgM, IgG, complement proteins, and antigens deposited in tissues. Type IV hypersensitivity’s mediation is by macrophages, monocytes, and T cells. Infectious diseases and autoimmune involve this hypersensitivity in thei r reactions. Most hypersensitivity injuries develop due to interactions between antibodies and antigens or between sensitized T-lymphocytes and antigens. The general symptoms  accompanying the reaction depend on the involvement of either T-lymphocytes, or antibodies. During antibody involvement, immediate hypersensitivity results, while T-lymphocyte involvement results in delayed hypersensitivity reaction. Immediate hypersensitivity includes immune complex reactions, cytotoxic reactions, allergic reactions, and anaphylaxis. Delayed hypersensitivity includes infection allergies and contact dermatitis. Antibody Mediated Hypersensitivity vs. T-lymphocyte Mediated Hypersensitivity Antibody mediated hypersensitivity depends on the antigen nature, its frequency, and antigen contact route (Phillips, 2006 p11). It also depends on antibody type that reacts with the antigen. The initial antigen dose is known as sensitizing dose. On exposure, a latent period follows. Later, a dose of the sam e antigen, referred to as shocking or eliciting dose, sets off the reaction. This results in tissue damage. In T-lymphocyte mediated hypersensitivity, T-lymphocytes function rather than antibodies. These T-lymphocytes function in cell mediated immunity. They produce Lymphokines, which stimulate macrophage influx in order to perform phagocytosis. This results in immune response exaggeration. For both antibody mediated and T-lymphocyte mediated hypersensitivity reactions, local tissue destruction results. However, destruction of tissue by T-lymphocyte mediation occurs via phagocytosis. For antibody mediated hypersensitivity, reactions begin minutes after antigen administration (Phillips, 2006 p31). On direct administration of the antigen directly to the tissue, for example, injection or bee stings, a systemic reaction occurs. For instance, anaphylactic shock may result. When the contact involved is superficial, involving epithelial tissue, a localized reaction results, for example, ha y fever and asthma. These reactions can also be referred to as atopy or allergy. T-lymphocyte mediated hypersensitivity, on the other hand, requires one day or more in order to develop. It can manifest in the form of infection allergy, such as in the tuberculin test (Phillips, 2006 p34). A second manifestation of T-lymphocyte mediated hypersensitivity is contact dermatitis. Large blister like lesions accompany the reaction, with vesicles surrounded by redness. The vesicles usually itch intensely.

Principles of magic and the mechanical philosophy Essay

Principles of magic and the mechanical philosophy - Essay Example Additionally, there was enchaining or bonding. The images that he presents are very detailed with various planetary natures that are always in action. The central point of these images is to communicate to the pneuma which is the astral body of the human beings and also the spirit. The soul of the person who views these images is attracted by them and thus apprehends them thus giving the person knowledge and wisdom. Therefore, the emphases for Bruno is the fact that there are always chains and bonds formed that are capable of communicating to the human soul. The chains and bonds that are supreme he referred to as vincula in his magic. He further goes on to say that: â€Å"There are three gates through which the hunter of souls [animarum venator] ventures to bind: vision, hearing and mind or imagination. If it happens that someone passes through all three of these gates, he binds most powerfully and ties down most tightly† (Bruno, 1997, p.155).In her book, the death of nature, Carolyn Merchant attempts to document the ecological and economic changes that were ongoing in Western Europe in the late 16th and early 17th century. Sweeping changes in both ecology and technology made it possible for there to be material conditions which facilitated the existence of new ideas. Although she cautions that her argument does not wholly support that material changes did not necessarily lead to ideological changes, she says that there are some ideas that appear more prevalent than others in a given period of time.in time. Furthermore, she claims that some ideas like those associated with magic and an organic view of the world become less compelling whereas the mechanical approaches are developed and adopted. There seems to be a back and forth argument in The Death of Nature between the social conditions as well as material conditions associated with nature and science. The strongest ideas are however those that are in support of the