Immunity PDF

❑ Antibodies: Antibodies are proteins known as immunoglobulins Demonstrate specificity 5 immunoglobulin subclasses: IgG, IgA, IgM, IgD and IgE Functions of antibodies Agglutinition – Ag – Ab reaction Neutralization - antibodies cover the toxic sites of the antigenic agent Lysis...

❑ Antibodies: Antibodies are proteins known as immunoglobulins Demonstrate specificity 5 immunoglobulin subclasses: IgG, IgA, IgM, IgD and IgE Functions of antibodies Agglutinition – Ag – Ab reaction Neutralization - antibodies cover the toxic sites of the antigenic agent Lysis - some antibodies are capable of directly attacking and rupturing cellular agents B lymphocyte  Processing and Presentation of Antigens Exogenous Antigens Endogenous Antigens Antigens Processed Thru Endocytic Pathway Antigens Processed Thru Cytosolic Pathway Binding of Ags To MHC II Produced Within Cell, Ex. Virus Ag, Cancer Ag Expression of MHC II+Ags On Surface MHC I Molecules Bind Ag in ER CD4 T Cells Recognize Ag Thru Class II MHC CD8 T Cells Recognize Ag Thru MHC I Types of immunity * There are mainly two types of immunity, innate and adaptive. Innate Immunity (native immunity): * It is considered the first line of defense against pathogens. * This immunity is non-specific in action: 1. Physical and chemical barriers (skin, mucous as well as body secretions like saliva, gastric juices, and vaginal secretions). 2. Cellular (WBCs): basophils, eosinophils, dendritic cells, and certain phagocytic cells such as macrophages, Natural killer (NK) cells, and neutrophils. 3- Humoral mechanisms: lysozymes, basic proteins, complement, interferons Adaptive immunity (acquired immunity): Unlike the innate immune system, which attacks only based on the identification of general threats, the adaptive immunity is activated by exposure to pathogens, and uses an immunological memory to learn about the threat and enhance the immune response accordingly. * The adaptive immune response is much slower to respond to threats and infections than the innate immune response, which is primed and ready to fight at all times.  Adaptive Immunity Displays four (4) attributes: 1) antibody specificity – distinguishes minute differences in molecular structure to determine non-self antigens. 2) diversity – the immune system can produce a hugely diverse set of recognition molecules which allows us to recognize literally billions of molecular shapes 3) memory – once it has responded to an antigen, the system maintains a memory of that Ag 4) self-nonself recognition –the system typically responds only to foreign molecules  S.N. Characteristics Humoral Immunity Cell-mediated Immunity The immunity mediated by macromolecules found in the The immunity that identifies and 1. Definition extracellular body fluids is called destroys infected cells in the body humoral immunity. (“humor” a is called cell-mediated immunity. medieval term for body fluid) The main cell involved in humoral The main cell involved in cell- 2. Mediator immunity are B-cells. mediated immunity are T-cells. Helper T cells, cytotoxic T-cells, 3. Components B cells, T cells, and macrophages. natural killer cells, and macrophages. The humoral immunity protects The cell-mediated immunity protects 4. Pathogen against extracellular pathogens and against intracellular pathogens. also their toxin. It responds to any cell that Recognize antigens or pathogens displays aberrant MHC markers, 5. Pathogen recognition that are circulating in the lymph or including cells invaded by blood. pathogens, tumor cells, or transplanted cells.  Only the T helper cell (CD4+) is Both CD4+ and CD8+ T cells are 6. Type of T-cell involved involved. involved. Antibodies are formed in a humoral Antibodies are not formed in a cell- 7. Antibodies formation response. mediated immune response. 8. Onset The onset is rapid. The onset is delayed. The end result of the activation is The end result of the activation is 9. Result the differentiation of plasma B- the secretion of cytokines. cells, secreting antibodies. It protects against fungus, viruses, Extracellular bacterial or viral 10. Protection against and intracellular bacterial pathogens. pathogens. As it destroys the tumor and cancerous It does not provide immunity against 11. Immunity against cancer cells, it provides protection against cancer. cancer.  Blood Plasma 1. Plasma proteins. 2. Other plasma solutes. 3. Functions of plasma. Blood Plasma ❑ Like other fluids in the body, plasma is composed primarily of water: In fact, it is about 92 percent water. ❑ Dissolved or suspended within this water is a mixture of substances, most of which are proteins. There are literally hundreds of substances dissolved or suspended in the plasma, although many of them are found only in very small quantities. Plasma proteins ❑ About 7 percent of the volume of plasma—nearly all that is not water—is made of proteins. ❑ These include several plasma proteins (proteins that are unique to the plasma), plus a much smaller number of regulatory proteins, including enzymes and some hormones. ❑ The three major groups of plasma proteins are as follows: 1- Albumin ❑ It is the most abundant of the plasma proteins. ❑ It is manufactured by the liver, albumin molecules serve as binding proteins—transport vehicles for fatty acids and steroid hormones. Recall that lipids are hydrophobic; however, their binding to albumin enables their transport in the watery plasma. ❑ Albumin is also the most significant contributor to the osmotic pressure of blood; that is, its presence holds water inside the blood vessels and draws water from the tissues, across blood vessel walls, and into the bloodstream. This in turn helps to maintain both blood volume and blood pressure. ❑ Albumin normally accounts for approximately 54 percent of the total plasma protein content. 2- Globulins ❑ There are three main subgroups known as alpha, beta, and gamma globulins. The alpha and beta globulins transport iron, lipids, and the fat- soluble vitamins A, D, E, and K to the cells; like albumin, they also contribute to osmotic pressure. ❑ The gamma globulins are proteins involved in immunity and are better known as an antibodies or immunoglobulins. ❑ Although other plasma proteins are produced by the liver, immunoglobulins are produced by specialized leukocytes known as plasma cells. ❑ Globulins make up approximately 38 percent of the total plasma protein volume. 3- Fibrinogen ❑ Like albumin and the alpha and beta globulins, fibrinogen is produced by the liver. ❑ It is essential for blood clotting. Fibrinogen accounts for about 7 percent of the total plasma protein volume. Other Plasma Solutes (nonprotein solutes) Plasma contains a wide variety of other substances that contribute approximately 1 percent to the total volume of plasma: Various electrolytes, such as sodium, potassium, and calcium ions Dissolved gases, such as oxygen, carbon dioxide, and nitrogen various organic nutrients, such as vitamins, lipids, glucose, and amino acids Metabolic wastes. Functions of plasma As plasma forms the liquid base of blood, the functions carried out by plasma and blood overlap. The multitude of functions include: 1. Coagulation: fibrinogen plays a major role in blood clotting along with other procoagulants like thrombin and factor X. 2. Defense: immunoglobulins and antibodies in plasma play an important role in the body’s defense against bacteria, viruses, fungi, and parasites. 3. Maintenance of Osmotic Pressure: the colloidal osmotic pressure by the plasma proteins like albumin synthesized by the liver. 4. Nutrition: transportation of nutrients like glucose, amino acids, lipids, and vitamins absorbed from the digestive tract to different parts of the body act as a source of fuel for growth and development. 5. Respiration: transportation of respiratory gases, i.e., carrying oxygen to the various organs and carrying carbon dioxide back to the lungs for excretion. 6. Excretion: the blood removes nitrogenous waste products produced after cellular metabolism and transports them to the kidney, lungs, and skin for excretion. 7. Hormones: hormones are released into the blood and transported to their target organs. 8. Regulation of Acid-Base Balance: plasma proteins contribute to acid- base balance through their buffering action. 9. Regulation of Body Temperature: this is maintained by balancing heat loss and heat gain in the body. 10. Role in Erythrocyte Sedimentation Rate (ESR): fibrinogen, an acute phase reactant, increases during acute inflammatory conditions and contributes to the increase in ESR, which is used as a diagnostic and prognostic tool.