Immunology

1. Immunology • Immunology is a broad branch of biomedical science that covers the study of all aspects of the immune system in all organisms. • It deals with • The physiological functioning of the immune system in states of both health and disease • Malfunctions of the immune system in immunological disorders (autoimmune diseases, hypersensitivities, immune deficiency, transplant rejection) • The physical, chemical and physiological characteristics of the components of the immune system.

2. Immune system • An immune system is a system of biological structures and processes within an organism that protects against disease by identifying and killing pathogens and tumor cells. • It detects a wide variety of agents, from viruses to parasitic worms, and needs to distinguish them from the organism's own healthy cells and tissues in order to function properly. • Immune system composed of: • Bone marrow, spleen, lymphatic system and thymus

4. Innate Immunity • Theinnate immune systemcomprises the cells and mechanisms that defend the host from infection by other organisms, in a non-specific manner. • Innate immune systems provide immediate defense against infection, and are found in all classes ofplantandanimallife. • Everyone is born with innate (or natural) immunity, a type of general protection that humans have.

5. Innate immunity includes • Anatomical barriers to infections • Mechanical factors eg. the epithelial surfaces give a protection for body organs • Chemical factors eg. fatty acids in sweat inhibit the growth of bacteria. • Biological factorsThe normal flora of the skin and in the gastrointestinal tract can prevent the colonization of pathogenic bacteria by secreting toxic substances for pathogenic bacteria • Humoral barriers to infectioneg. Complement system, coagulation system, interferons, lysozyme • Cellular barriers to infectionNeutrophils, macrophages, eosinophils

6. Adaptive (active) Immunity • This type of immunity develops throughout our lives. • Adaptive (active) immunity involves the lymphocytes and develops as children and adults are exposed to diseases or immunized against diseases through vaccination.

7. Passive Immunity • Passive immunity is "borrowed" from another source and it lasts for a short time. • For example, antibodies in a mother's breast milk provide an infant with temporary immunity to diseases that the mother has been exposed to. This can help protect the infant against infection during the early years of childhood.

8. Antibodies(immunoglobulins) • Antibodiesaregamma globulinproteinsthat are found inbloodor otherbodily fluidsofvertebrates, and are used by theimmune systemto identify and neutralize foreign objects, such asbacteriaandviruses. • Antibodies are produced by a kind ofwhite blood cellcalled aplasma cell. • There are five different antibody isotypes are known in mammals (IgM, IgG, IgA, IgE, IgD) • These isotypes are perform different roles, and help direct the appropriate immune response for each different type of foreign object they encounter.

10. Antigen and immunogen • Anantigenis a molecule recognized by theimmune system. Originally the term came fromantibodygeneratorand was a molecule that binds specifically to anantibody • Self antigens are usually tolerated by the immune system; whereas "Non-self" antigens are identified as intruders and attacked by the immune system. • Immunogenis a specific type of antigen. An immunogen is defined as a substance that is able to provoke an adaptive immune response if injected on its own • Said another way, an immunogen is able to induce an immune response, while an antigen is able to combine with the products of an immune response once they are made.

11. Pathogen • Apathogen, (from Greek πάθος pathos "suffering, passion", and γἰγνομαι (γεν-) gignomai (gen-) "I give birth to") • Aninfectious agent, or more commonlygerm, is abiological agentthat causesdiseaseto itshost • Pathogen may be bacteria, virus, fungi, parasite, protozoa, parasite, tumor cells or self proteins.

12. complement system • Thecomplement systemis abiochemical cascadethat helps, or “complements”, the ability of antibodies to clearpathogensfrom an organism. • The complement system consists of a number of small proteins found in the blood, generally synthesized by theliver, and normally circulating as inactive precursors )pro-proteins) • Stimulation of these proteins result in the activation of the cell-killingmembrane attack complex.

13. Inflammation InflammationLatin, inflammare, to set on fire • Is part of the complex biological response ofvasculartissues to harmful stimuli, such aspathogens, damaged cells, or irritants • It is characterized by • increased blood flow to the tissue causing • increased temperature, • redness, • swelling, and • pain. • Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process..

14. Histamine • Histamineis an organic nitrogen compound involved in localimmune responsesas well as regulating physiological function in the gut and acting as aneurotransmitter • Histamine triggers theinflammatory response. • As part of an immune response to foreignpathogens, histamine is produced bybasophilsand bymast cellsfound in nearby connective tissues. • Histamine increases the permeability of the capillaries to white blood cells and other proteins, in order to allow them to engage foreign invaders in the infected tissues

15. Allergy • Is ahypersensitive disorderof theimmune system. • Allergic reactions occur to normally harmlessenvironmentalsubstances known asallergens; these reactions areacquired, predictable, and rapid. • Allergy is one of four forms ofhypersensitivity. • It is characterized by excessive activation of certainwhite blood cellscalledmast cellsandbasophilsby a type ofantibodyknown asIgE, resulting in an extremeinflammatoryresponse. • Common allergic reactions includeeczema, hives, hay fever, asthmaattacks, food allergies, and reactions to thevenomof stinginginsectssuch aswaspsandbees.

16. Autoimmunity • Is the failure of an organism to recognize its own constituent parts asself, which allows an immune response against its own cells and tissues. • Any disease that results from such an aberrant immune response is termed anautoimmune disease. • Prominent examples include • Systemic lupus erythematosus (SLE • Rheumatoid arthritis (RA

17. Transplant rejection • Transplant rejectionoccurs when atransplantedorgan or tissue is not accepted by the body of the transplant recipient. • This is explained by the concept that theimmune systemof the recipient attacks the transplanted organ or tissue. • This is expected to happen, because the immune system's purpose is to distinguish foreign material within the body and attempt to destroy it, just as it attempts to destroy infecting organisms such asbacteriaandviruses • When possible, transplant rejection can be reduced throughthe use ofimmunosuppressant drugs

18. Diagnostic immunology • The specificity of the bond between antibody and antigen has made it an excellent tool in the detection of substances in a variety of diagnostic techniques. • Antibodies specific for a desiredantigencan be conjugated with a radiolabel, fluorescent label, or color-forming enzyme and are used as a "probe" to detect it.