L1.pptx

L1.pptx

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  General Immunology Introduction: chronological developmentand scope of immunology. By Aleena Zafar
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  Immunology • Latin wordmeaning exempt • Protection from diseases • To rid the body from foreign particle eg microbes and abnormal cells • Our immune system response involves the interplay between our nonspecific and specific immune responses
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  Defense system • Inthe process of evolution, the body of organisms has developed the property of distinguishing • “self” and “nonself”, • the “self” is accepted and “nonself” is rejected or degraded. • For the rejection or degradation of “nonself”, organisms’ body has evolved a remarkably versatile defence system called immune system that operates via various mechanisms, which are collectively grouped under the name immunity or resistance (defence).
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  General overview ofimmune system • Innate immunity Fast acting Less specific recognition Early during evolution e.g barrier to the infection such as skin and mucus • Adaptive immunity Specificity Memory and recall
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  Conti.. • Cells ofimmune system Leucocytes originating from bone marrow cells • Disruption of immune system Allergy Autoimmunity immunodeficiency
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  History • Immunology isclaimed to have emerged out of some observations in the ancient past. The ancient people observed that individuals who had recovered from certain infectious disease were not attacked by the same disease again, i.e., they became immune to the disease. • Another important observation dates back to 430 BC when Thucydides, the great historian of the Peloponnesian War, wrote that only those individuals who had recovered from the plague would not contract the disease a second time, and could nurse the plague patients. Thucydides’s observation is perhaps the earliest written reference to the phenomenon of immunity.
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  Development of Vaccination: •The first recorded attempts to induce immunity deliberately were made by Chinese and Turks in the 15th century. They either inhaled the dried crusts derived from small pox pustules or inserted them into small cuts in the skin (this technique is called variolation). • Lady M.W. Montagu, the wife of the British ambassador to Constantinople, observed in 1718 that there were positive effects of the technique of variolation applied on to the native population. She also applied this technique on her own children and found the positive results.
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  • The techniqueof variolation was significantly improved by Edward Jenner, an English physician, in 1798. He was intrigued by the fact that milkmaids, who had contracted the mild disease cowpox, became immune to the dreaded smallpox. Jenner reported to the Royal Society in London the value of immunization with cowpox as a means of protecting against smallpox; a clear case of vaccination. • Thus, he did on the basis of the fact that when he inoculated a 8-year old boy, James Phipps, with cowpox content, the boy escaped from smallpox infection. Jenner’s explanation regarding cowpox vaccination against smallpox established the scientific credibility of vaccination to prevent disease and was accepted by the scientists and physicians of the time.
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  Discovery of Phagocytosisand Cell- Mediated Immunity: • In 1883, a Russian scientist Elie Metchnikoff while studding infection of the common water-flea (Daphnia) by a fungus demonstrated that certain white blood cells, which he termed phagocytes, were able to ingest (phagocytose) microbial pathogens and other foreign substances. This was the first demonstration of the process of phagocytosis. • Moreover, noting that these phagocytic cells were more active in immunized animal and contribute to its immune state, Metchnikoff hypothesized that cells were the major effector of immunity and gave the concept of cell-mediated immunity.
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  Discovery of HumoralImmunity: • Von Behring and Kitasato demonstrated in 1890 that serum (the liquid, non-cellular component of coagulated blood) from animals previously immunized to diphtheria could make unimmunized animals immune to the disease when it was administered to the latter. • Since it was a discovery which showed that the immunity was mediated by non-cellular body fluids (known at the time as humors), the door of humoral immunity was opened. • For this discovery, Behring was awarded Nobel prize in 1901. Humoral immunity, however, was fully confirmed only during 1930s mainly through the efforts of Elvin Kabat and other workers who demonstrated that a fraction of scrum called gamma-globulin (now called immunoglobulin or antibodies) was found responsible for immunity acquired following immunization.
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  Scope of Immunology •Our knowledge of the immunological processes underlying the reactions of the body to infectious agents, to tumours, and to transplanted tissues and organs has advanced remarkably by using modern techniques, including those developed by biochemists and molecular biologists. • These techniques have enabled the identification of genes coding for molecules like the T-cell receptor and MHC molecules. The genes coding for immunologically important molecules have been cloned and relatively large amounts of pure recombinant proteins have been produced.
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  • It isnow possible to culture many different cell types in vitro and to clone these cells so that a population with an identical genetic makeup is obtained. • Many different strains of inbred mice, including ‘knock-out’ and ‘knock-in’ mice, have been developed for the investigations of cellular interactions, gene inactivation’s, etc. The role of a number of gene products has been elucidated by producing transgenic animals and studying the effect of the introduced genes.
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  • Immunologists havedeveloped many new techniques, including novel ways of producing a homogeneous immunoglobulin preparation, viz., monoclonal antibody, by using impure antigens. The development of these strictly defined reagents revolutionalized immunoassays and detection systems that employ antibodies. • Their potential in the treatment of infectious diseases, cancer patients, organ transplants, etc. is being actively investigated and a number of clinical trials have been performed. In addition to antibodies, other immunologically important molecules have been produced and are being developed as therapeutic agents.
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  • The introductionof flow cytometry has revolutionized the analysis of cell populations and the use of polymerase chain reaction has increased the sensitivity of the detection of microorganisms. • The interplay between cells and molecules of the immune system is extremely complex. We are only now beginning to understand the intricacies of immune recognition. Some molecules appear to have many different functions depending on their location or the presence of other molecules.
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  • The possibilityof harnessing these powerful reagents to aid the elimination of not only pathogenic microorganisms, but also cancer cells is being actively pursued. • The ability to predict the minimum structures that can induce protective immunity will allow the development of more effective and safer vaccines. It may also become possible to develop novel ways of treating autoimmune diseases, allergic conditions and tumours, and to develop new strategies to reduce transplant rejection.
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  • Thus itcan be seen that immunity in its original meaning, referring to resistance to infections by means of a specific immune response, is only one activity of a complex system in animals. • The total activity of the cellular system is concerned with mechanisms for preserving the integrity of the individual with far-reaching implications in embryology, genetics, cell biology, tumor biology and many non-infectious disease processes.