IMMUNITY

• IMMUNITY - It is the ability to resist damage from foreign substances:
• INNATE IMMUNITY - The body recognizes and destroys certain foreign substances, but the response to them is the same each time the body is exposed
• Physical Barriers - Prevent microorganisms and chemicals from entering the body through
• Chemical Mediators - These are molecules responsible for many aspects of innate immunity
• Complement

  •A group of approximately 20 proteins found in the plasma

  •It normally circulate in the blood in an inactive form
• Interferons - Proteins that protect the body against viral infections
• White Blood Cells - The most important cellular components of immunity
• Phagocytic Cells - Phagocytosis is the ingestion and destruction of particles by phagocytes
• Neutrophils - Small phagocytic cells that are usually the first cells to enter infected tissues from the blood in large numbers
• Pus - an accumulation of fluid, dead neurophils, and other cells at a site of infection
• Macrophages - Monocytes that leave the blood, enter tissues and enlarge about fivefold
• Basophils - Motile white blood cells that can leave the blood and enter infected cells
• Mast Cells - Non-motile cells in connective tissue, especially near capillaries
• Natural Killer (NK) Cells

  •A type of lymphocyte produced in red bone marrow, account up to 15% of lymphocytes

  •It recognizes classes of cells, such as tumor cells or virus-infected cells, in general, rather than specific tumor cells or cells infected by a specific virus

  •They do not exhibit a memory response
• Vasodilation - Increases blood flow and brings phagocytes and other WBC to the area
• Local Infection - An inflammatory response confined to a specific area of the body
• Systemic Inflammation - Response that is generally distributed throughout the body
• Specificity - the ability to recognize a particular substance
• Memory - the ability to respond with increasing effectiveness to successive exposures to the antigen
• Antigens - Are substances that stimulate adaptive immune response
• Foreign Antigens - Introduced from outside of the body
• Self-antigens

  •Molecules the body produces to stimulate an immune system response

  •It can be beneficial such as recognition of tumor antigens

  •It can also be harmful such as in an autoimmune disease wherein the self-antigens stimulate unwanted destruction of normal tissue
• Antibodies

  •Are proteins produced in response to an antigen

  •They make up the large portion of proteins in the plasma
• IgG - Activates complement system and increases phagocytosis
• IgM

  •Activates complement and act as antigen-binding receptor on the surface of B cells

  •Responsible for transfusion reaction in the ABO blood system
• IgA

  •Secreted into saliva, into tears, and onto mucous membrane to protect body surfaces

  •Found in the colostrum and milk to provide immune protection to the newborn
• IgE - Binds to mast cells and basophils and stimulates the inflammatory response
• IgD - Functions as an antigen-binding receptor on B cells
• Plasma Cells

  •Produce antibodies

  •Primary response normally takes 3-14 days to produce enough antibodies to be effective against the antigen
• Memory B Cells

  •Responsible for the secondary response (memory response) which occurs when the immune system is exposed to an antigen against which it has already produced a primary response
• Cell-Mediated Immunity - It is a function of cytotoxic T cells and is most effective against microorganisms that live inside body cells.
• Active Natural Immunity

  •Results from natural exposure to an antigen, such as disease-causing microorganism, that stimulates the immune system to respond against the antigen
• Active Artificial Immunity

  •An antigen is deliberately introduced ito an individual to stimulate the immune system through vaccination
• Passive Natural Immunity

  •Results when antibodies are transferred from a mother to her child across the placenta before birth.
• Passive Artificial Immunity

  •Provides immediate protection because the antibodies either directly or indirectly destroy the antigen