1. IMMUNITY Walter Benitez Caryn Crabb Alex Flores Annie Truong Courtney Vazquez

2.  IMMUNITY is the protection against infectious diseases, it can be gained either actively or passively  Protection against diseases are provided by the body’s defense or the IMMUNE SYSTEM DEFENSE AGAINST DISEASE

3. EXTERNAL DEFENSE SYSTEM  Humans have many mechanisms to protect themselves against infectious diseases  When we are healthy, physical, chemical, and cellular defenses prevent pathogens from entering the body  Hydrochloric acid that is found in the stomach kills off bacteria that is ingested with many food and drinks  Blood clotting is a defense mechanism that prevents the loss of blood and prevents pathogens from entering the body through wounds in the skin

4. INTERNAL DEFENSE SYSTEM  If and when pathogens enter the body, white blood cells recognize them as foreign cells and kills them off  The foreign cells are called ANTIGENS. White blood cells are able to recognize these cells because they have distinctive large molecules that cover their surface  There are two types of white blood cells: PHAGOCYTES and LYMPHOCYTES  Some lymphocytes produce ANTIBODIES, which are protein molecules that act against specific antigens  Cell surface antigens are molecules on the surfaces of our cells that are not found in other organisms, or even humans.  Responsible for determining whether or not to produce antigens  The response of lymphocytes to the presence of a foreign antigen is known as the IMMUNE RESPONSE

5. EXAMPLE FOR INTERNAL DEFENSE SYSTEM  Cell surface antigens are used to recognize the foreign and non-foreign cells  If a transfusion of, say blood type B to blood type A, is made, then the blood type A will be recognize the type B as a NON-SELF and create antigens. If it were type B to type B, then it would recognize as SELF and not create antigens

6. CELLS OF THE IMMUNE SYSTEM  There are two groups of white blood cells in the immune system: Phagocytes and Lymphocytes

7. PHAGOCYTES  Produced throughout life in bone marrow where they remove dead cells  Types of phagocytes:  Neutrophils: short lived cells that are released in large numbers during infections  Travel throughout the body, leaving the blood squeezing through the wall of capillaries to “patrol” the tissues  These die after killing and digesting some pathogens  Macrophages: long lived cells that are larger than neutrophils  Play a crucial role in initiating immune responses, then cut up pathogens to display antigens that can be recognized by lymphocytes  Made in the bone marrow and travel in the blood MONOCYTES which become monophages once they leave the blood and settle in the organs  These are found in the liver, spleen, kidney, and lymph nodes

8. PHAGOCYTOSIS  Histamines: the chemicals released by cells when pathogens invade the body causing an infection  These attract passing neutrophils to the site. The neutrophils destroy the pathogens by phagocytosis.  The stages of phagocytosis are:  Attraction  Recognition and Attachment  Endocytosis  Bacteria with a phagocytic vacuole  Fusion of lysosomes and phagocytic vacuole  Killing and Digestion

9. LYMPHOCYTES  Plays an important role in immune response  Lymphocytes are smaller than phagocytes  Only mature lymphocytes can carry out immune responses

10. B-LYMPHOCYTES  While the B cells mature, the gene codes change in a variety of ways to code for different antibodies  they then divide into smaller identical cells called Clones  Antigen presentation- when the pathogens first invade the body, some of them are taken up by macrophages in lymph nodes and elsewhere; the macrophages expose the antigens from the pathogens on their surfaces.  Macrophages are also called Antigen Presenting Cells or APC’s  Clonal selection- the stage where B cells that fit the antigens interact with the macrophages are selected to respond.  Clonal expansion stage- when the small clone of cells divides repeatedly by mitosis

11. B-LYMPHOCYTES  B- Lymphocytes become  Plasma Cells & Memory Cells  Plasma Cells  Secret antibodies into the blood, lymph or onto the lining of the lungs and the gut.  Memory Cells  After the fist infection, cells divide rapidly and develop into plasma cells and more memory cells. The infection can be destroyed and removed before any symptoms of disease can develop  These are the basis of immunological memory.

12. Response  The first or primary response is slow because at this stage, there are very few B cells that are specific to the antigen.  The secondary response is faster because there are many memory cells which divide and differentiate into plasma cells.

13. Antibodies  Antibodies – globular glycoproteins  Form immunoglobulins from grouping of plasma proteins.  Made of four polypeptide chains. Two long/heavy and two short/light; these chains are held together by disulfide bonds.  Each molecule has two identical antigen binding sites  The antigen-binding sites form the variable region, which is different on each molecule.  Some antibodies act as labels to identify antigens as appropriate targets for phagocytes to destroy.  Antitoxins- block the toxins released by bacteria. Can cause diphtheria and tetanus.

14. T-lymphocytes  Mature T cells have specific surface receptors called T cell receptors, which have a structure that is similar to antibodies  T cells are activated when they encounter their specific antigen on another cell of the host  Two main types: T helper cells and Killer T cells  When the helper T cell is activated they release hormone- like cytokines that make appropriate B cells start to divide, which then turn into plasma cells and secrete antibodies  Some cytokines stimulate macrophages to help carry out phagocytosis more vigorously

15. T-lymphocytes  Killer T cells search for cells that have become invaded by pathogens  Recognize antigens then attach themselves to the surface of the infected cells and secrete toxic substances (hydrogen peroxide) which then kill the body cells and the pathogens inside  Memory T helper cells and memory killer T cells are created and stored in the body, becoming active during the secondary response to antigens  http://kidshealth.org/kid/htbw/ISmovie.html http://kidshealth.org/kid/htbw/ISmovie.html

16. Active Immunity  Active immunity is when the body produces their own antibodies  Lymphocytes (B&T) are activated by antigens on the surface of pathogens that invade the body  B & T cells are produced to give an effective defense  Two types  Natural active immunity occurs naturally in the body during an infection  If the immune response is injected it is artificial active immunity

17. Passive Immunity  Passive immunity is when a person doesn’t produce their own antibodies and receive their antibodies from another person who contains the antigen.

18. Types of Passive Immunity  Artificial Passive Immunity  Tetanus kills quickly before the body can naturally produce antibodies  Those with the wound are injected with antitoxin that is collected from blood donors who have recently been vaccinated against tetanus Natural Passive Immunity While in the womb the mother passes her antibodies to the child through the placenta After the child is born the antibodies remain in the child for months Colostrum is also breast fed to the child within the first week after the child’s birth that contain antibodies http://www.youtube.com/watch?v=PNTDpx srNGM

19. Vaccination  Vaccines are preparations used to stimulate an immune response artificially either injected or given orally  Contain either:  A live microorganism  A dead microorganism  A harmless version (attenuated organism)  Harmless form of a toxin (toxoid)  Preparation of surface antigens

20. Vaccination  Vaccines try to mimic the body’s natural immunity  This works particularly well in live microorganism vaccines because the microorganism produces slowly facing the immune system with large doses of antigens, allowing it time to create antibodies  Vaccines that are less effective are those that don’t mimic an infection because they contain dead bacteria or viruses that don’t replicate inside the body

21. Problems with Vaccines  Some people have poor response or no response at all to vaccines caused by  A defective immune system: body doesn’t develop B & T clone cells  Or suffer from malnutrition: the body can’t produce enough protein to make antibodies or clones of B & T cells.

22. Heard Immunity  To prevent people who have no immunity from picking up diseases vaccination is better through a large group of people at the same time which is known as heard immunity  When children are born, vaccination occurs within a few months after birth

23. Antigenic Variation  The influenza virus mutates regularly to give off different antigens  The minor changes are called antigenic drifts  Serious changes in antigen structure is an antigenic shift

24. Plasmodium  Plasmodium causes malaria and exists in three stages  An effective vaccine would need to contain antigens of all three stages  The immune system would need to give an effective response in the matter of hours  RTS is an experimental vaccine, reduces the risk of young children being infected by half and reduces the chance of facing the most serious part of the disease by a third

25. Trypanosoma  Trypanosoma is the agent that causes sleeping sickness  Contains thousands of antigens and changes them every four to five days  Making it impossible for the body to respond effectively

26. Antigenic Concealment  Antigens can be known to hide from the immune system  Plasmodium enters red blood cells and uses the plasma to protect from antibodies  Pathogens can invade macrophages and T cells to suppress the immune system

27. Eradication of Smallpox  Smallpox was a highly infectious disease caused by the variola virus  transmitted through direct contact and killed between 12-30% of its victims  The Who started a program to rid smallpox world wide  The program had two aspects  Vaccination  Surveillance  If someone declared a case of the small pox that household and the surrounding households were vaccinated for smallpox, known as ring vaccination  Through ring vaccination The WHO declared the world free of small pox in 1880

28. How Smallpox Was Eradicated  The variola virus was stable and didn’t mutate  Vaccine was made from a harmless strain of a similar virus, effective because it was a live vaccine  Vaccine was freeze dried and kept for months  Infected people were easily identified  Vaccine was easy to administer  Virus didn’t linger in body after infection  Virus didn’t infect people  http://www.youtube.com/watch?v=zi5HIMgQCEA http://www.youtube.com/watch?v=zi5HIMgQCEA

29. Measles  Caused by a virus which is spread through airborne droplets  Rarely affects infants under 8 months  Passive immunity as antibodies that have crossed the placenta from their mother  Vaccinations have the decreased the amount of children affected by measles  The majority of cases in the US are brought from abroad  Measles in cities are caused by: overcrowded homes, insanitary conditions, and high birth rate and usually affect malnourished and Vitamin A deficient infants  Responsible for cases of childhood blindness and severe brain damage

30. Prevention  Vaccination is the best prevention  Most countries achieve 80% coverage of measles vaccination