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Type - 1 Hypersensitivity Reaction

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Introduction

Sensitised Guinea Pig Ileum. (Hypersensitivity type1) Aims. An experiment was conducted to investigate hypersensitivity type 1 (allergic reactions) and the effects that different doses (0.2 10-4 m and 0.4 10-4 M) of histamine had on the guinea pig ileum (tissue). The different effects that mepyramine and carbachol had on the guinea pig ileum were also investigated. A piece of tissue from a guinea pig's ileum, which had been 1, non-sensitised and 2, sensitised to egg albumin were exposed to mepyramine, carbachol and different doses of histamine. The experiment was to illustrate any differences that occurred between the sensitised guinea pig ileum and the non-sensitised guinea pig ileum. The control experiment was the non-sensitised guinea pig's ileum (tissue). Introduction. The immune/ inflammatory system is designed to fight against infections foreign substances/molecules that invade the body, these foreign substances can be specifically recognised by the white cells in the blood stream. T-Lymphocytes pass through the bloodstream, lymph nodes and the connective tissues searching out foreign substances i.e. antigens, which are located on pathogens and abnormal cells. The immune system is divided into two classes, the innate system (natural immunity) and the innate system, which is not capable of specifically recognising antigens, and resistance to infection is not determined by a returning infection, given that it does not stimulate the memory cells. However basophils and macrophages (antigen presenting cells) do play an important role with respect to effector cells in cell-mediated immunity. T-cells recognise protein antigens (foreign molecules), which are presented to them by the macrophages. Antigens are foreign molecules found on viruses, bacteria and fungi, pollen and toxins and can induce an immune/allergic response, i.e. allergies. "Allergens are usually specific protein antigens (pep-tides) that stimulate immune hypersensitivity by reacting with IgE or IgG antibodies and T-cells". Current Allergy & Clinical Immunology, March 2004 Vol 17, No. 1 The other class of immunity is known as the adaptive immunity (antibody mediated immunity), which is mediated by B-lymphocytes and is differentiated into active and passive immunity. ...read more.

Middle

Lai FM, Cobuzzi A, Spinelli W Results. The results that were recorded here are of a qualitative data, please see diagrams below text. Different dilutions of histamine were used in the first experiment this was to see which histamine would give the greatest response. Because the two responses were different from each other and it was decided that the 0.2 ml and 0.4 ml of histamine at 10-4 M was the most effective therefore this was the dilution that was used in the entire experiment. Also carbachol and mepyramine was a 10-4 molar. Non-sensitised tissue Control, when the 0.4 and 0.2 ml of 10-4 M histamine was added there was a contractile response in the guinea pig ileum. However the oscillograph measured a higher contractile response when 0.4 10-4 M of histamine was used opposed to the 0.2 10-4 M of histamine. There was no response when on both occasions that the 1ml of egg albumin was added to the guinea pig ileum tissue. Seeing that this tissue was not sensitised to egg albumin this result would be correct because no mask cells were available to release histamine, i.e. antibodies were not available to elicit an immune response. When the 0.2 ml of 10-4 mepyramine was added a contractile response was not seen possibly because mepyramine is an antagonist that also binds onto h1 receptors and the receptors already had the histamine bound onto them, thus blocking a response to mepyramine. When the 0.4 ml of 10-4 M of carbachol (with no wash in-between time) was added a contractile response was seen and recorded. Carbachol was possibly used to demonstrate that the tissue was still alive. The oscillograph measured sensitised tissue 1 and when 0.2 and 0.4 ml of 10-4 M of histamine was added a contractile response, was noted and this was recorded. When 1 ml of egg albumin was added the first time there was a contractile response. ...read more.

Conclusion

Additionally it can be determined that this was an antibody mediated response directly involving the adaptive immune systems where it is highly specific on the first exposure to an antigen/egg albumin and produced memory B and T-lymphocytes consequently it made the distinction between the egg albumin evidently the immune/ inflammatory resistance was improved by a second bout of infection (second exposure to the egg albumin and it can be determined that this was an antibody mediated response directly involving the adaptive immune system. Some of the results obtained from this experiment are similar to results that were confirmed in a study that was investigated regarding people who were sensitised to asthma phenotype. This experiment involved taking small pieces of bronchial tissue segments, which were incubated with serum (and grown in culture) from a person who, via a skin test proved positive for allergens and a person's serum who was Non-allergic, the result was the person who was non-allergic had a lower concentration of IgE bearing cells where as the allergic person's serum contained a high level of IgE bearing cells. Also the amount of IgE bearing cells was significantly higher in people with passively sensitised serum the mast cells revealed a 65% of IgE bearing cells The results indicated that the mast cells were the main cell type involved in IgE induced passive sensitisation. "There are several different types of functional consequences of passive sensitization Bronchial ring segments exposed to allergic serum exhibit a contractile response to exogenous allergen, whereas segments from the same patient exposed to non-allergic serum do not. That IgE mediates this response and that the site of this reaction is mast cells located within the tissues is now well established. This evidence arises from studies in which chimeric IgE has been substituted for allergic serum (8), serum has been depleted of IgE (7), and anti-IgE has been substituted for allergen (13). Moreover, immunohistochemical analysis of passively sensitized tissue has revealed that there is an increase in IgE-bearing cells in these tissues and that these cells are principally mast cells." Am. J. Respir. Crit. Care Med. ...read more.

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