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Immunology

Immunology. Types of Immunity. Innate Adaptive Humoral Cell-Mediated Active Passive. Innate Immunity. Basic, immediate defense against invading pathogens Doesn’t attack singular pathogen Defends against all antigens Cellular and bodily defenses Phagocytosis of invading pathogens

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Immunology

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  1. Immunology

  2. Types of Immunity • Innate • Adaptive • Humoral • Cell-Mediated • Active • Passive

  3. Innate Immunity • Basic, immediate defense against invading pathogens • Doesn’t attack singular pathogen • Defends against all antigens • Cellular and bodily defenses • Phagocytosis of invading pathogens • Inflammation • Physical barriers

  4. Adaptive Immunity • Increased level of defense • Attacks specific pathogen • Memorizes that pathogen in case of future need • Mostly cellular responses • Divided into humoral and cell mediated immunity

  5. Humoral Immunity • Immunity using macromolecules • B cells • Type of lymphocyte that is formed in bone marrow • Possesses a protein on outer surface called B cell receptor • Antibodies/Immunoglobulins • Produced by B cells • Takes out bacteria and viruses • Complement System • Helps phagocytic cells clear pathogens • Causes cytolysis of target cell

  6. Cell Mediated Immunity • Involves cells such as phagocytes and cytotoxic T-lymphocytes instead of antigens • Activates cytotoxic T-lymphocytes to destroy infected cells • Turns on macrophages and NK cells • T-lymphocytes • Mature in thymus • Numerous types

  7. Active Immunity • Antibodies are produced when immune system is exposed to an antigen • Artificially acquired • Vaccines • Naturally acquired • Memory T cells

  8. Passive Immunity • Antibodies passed from one individual to another • Natural • Transfer of antibodies through placenta or colostrum • Artificial • Taking antibodies for a specific pathogen from immune individual to non-immune • Short duration

  9. Immunoglobulins • Mark cells for attack or destroy cells themselves • Five types • IgM • IgE • IgD • IgG • IgA

  10. IgM • Basic antibody produced by B cells • First antibody on site when host attacked by pathogen • “Precursor” to IgG • Defends host until IgG has attained high enough levels

  11. IgE • Found in lungs, skin and mucous membranes • Main purpose is defense against parasites such as worms and protozoans • Cause body to respond against pollen, dander • Primary immunoglobulin used for allergic reactions

  12. IgD • Role isn’t fully understood • Signals the activation of B cells • Plays part in allergic reactions • Assists with respiratory immune defense

  13. IgG • Major immunoglobulin of defense • Part of secondary immune response • This is the only antibody that can cross through the placenta • Causes agglutination of pathogens • Coats surface of foreign bodies for ingestion by phagocytes • Activates complement system

  14. IgA • Found in mucosal areas • Inhibits pathogen habitats • Immunoglobulin in colostrum and milk • Assists with the initiation of inflammation

  15. Developmental Immunology • Fetus has to start from scratch • No antibodies and no protection passed through placenta • First antibodies come from colostrum • Protects neonate until they can develop their own antibodies • Human fetus has antibody transfer from mother • Transfer across placenta • Additional amount from milk

  16. IgG in Human Fetus • Level of IgG in fetus are correlated to the level in mother • IgG must be bound to neonatal Fc receptor (FcRn) or face degradation by lysosomal enzymes • Certain regions of Africa showed limited transfer of IgG because FcRn was saturated with IgG (Palmeira, et al. 2012) • Fetus starts to acquire maternal antibodies beginning at the 13th week of gestation • Largest amount of transfer happens in third trimester • At full term, fetal IgG concentrations surpass the mothers by 20-30% • Maternal age, parity, weight and delivery type have no effect on IgG concentration

  17. Colostrum and its Role • First time neonate will receive antibodies from mother • Stomach is porous at birth to allow absorption • Absorption at max for first six hours post birth • Can acquire antibodies for up to 24 hours, but transfer hindered • Without adequate intake of colostrum, newborn will have less productive life • Higher risk of morbidity, mortality, decreased growth rates and first lactation milk production in dairy calves (Fidler, et al. 2007)

  18. Colostrum Components • Immune factors • Immunoglobulins, cytokines, lysozymes, glycoproteins • Growth factors • IGF-1, IGF-2, epithelial growth factor • Nutritional components • Vitamins, minerals, amino acids • Antibodies • IgG • IgA • IgM

  19. Changing Absorption of IgG • Difructose anhydride III • Indigestible disaccharide which promotes absorption of calcium and magnesium in intestines • Improves absorption of IgG in newborns • Feed colostrum in one feeding • Heat treated colostrum • Decreases microbial count while maintaining IgG levels

  20. Changing Absorption of IgG • Use of colostrum replacers • Colostrum replacers (CR) had less transfer of passive immunity when compared to colostrum (Fidler, et al. 2011) • However, the more CR the calves received, the better the transfer • Feeding sodium bicarbonate • NaHCO3 can increase IgG concentration up to a point (Cabral, et al. 2011) • Feed colostrum in two feedings

  21. Ig Deficiencies • Hypogammaglobulinemia • Lack or decrease of one or more types of antibodies • Fetuses that don’t receive antibodies through the placenta fall into this category • IgG deficiencies • More susceptible to infections such as pneumonia, bronchitis and others • Often occurs when there’s also a deficiency in IgA or IgM • Cause unknown but has possible genetic ties

  22. Autoimmune Diseases and Impact on Fetus • If mother suffers from an autoimmune disease, it can have a negative effect on the fetus • Immune thrombocytopenia • Maternal IgG antibodies can cross placenta and cause this in fetus • May lead to intracerebral hemorrhage during labor and higher risk of bleeding may be present before this time • Grave’s Disease/Hyperthyroidism • Thyroid stimulating autoantibodies can get to fetus and stimulate the fetus’ thyroid, causing intrauterine and neonatal hyperthyroidism

  23. Microchimerism • Possession of cells or DNA from a genetically different individual • Placenta thought to stop cell transfer between mother and fetus • Some cells leak through and can survive in the other body • Mother can have trophoblasts, mesenchymal stem cells, and immune system cells • This transfer is beneficial and detrimental • Possible increase in autoimmune diseases • May be able to discover fetal illness before birth • Can also happen between fetuses • Freemartins

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