Download to read offline
More Related Content
Similar to 109 Im mune-1.ppt
109 Im mune-1.ppt
- 1.
- 2. Types of immunity •Innate • Adaptive: – Humoral – Cell mediated Also classified as: – Passive: 1.Natural 2. Artificial – Active: 1. Natural 2. Artificial
- 3.
- 4. Cells of theImmune System White Blood Cells • Phagocytes - Neutrophils - Macrophages • Lymphocytes
- 5. Phagocytes • Produced throughoutlife by the bone marrow. • Scavengers – remove dead cells and microorganisms.
- 7. Neutrophils • 60% ofWBCs • ‘Patrol tissues’ as they squeeze out of the capillaries. • Large numbers are released during infections • Short lived – die after digesting bacteria • Dead neutrophils make up a large proportion of puss.
- 8. Macrophages • Larger thanneutrophils. • Found in the organs, not the blood. • Made in bone marrow as monocytes, called macrophages once they reach organs. • Long lived • Initiate immune responses as they display antigens from the pathogens to the lymphocytes.
- 9.
- 10.
- 11. Phagocytosis • If cellsare under attack they release histamine. • Histamine plus chemicals from pathogens mean neutrophils are attracted to the site of attack. • Pathogens are attached to antibodies and neutrophils have antibody receptors. • Enodcytosis of neutrophil membrane phagocytic vacuole. • Lysosomes attach to phagocytic vacuole pathogen digested by proteases
- 12. Lymphocytes • Produce antibodies •B-cells mature in bone marrow then concentrate in lymph nodes and spleen • T-cells mature in thymus • B and T cells mature then circulate in the blood and lymph • Circulation ensures they come into contact with pathogens and each other
- 13. B -Lymphocytes • Thereare c.10 million different B- lymphocytes, each of which make a different antibody. • The huge variety is caused by genes coding for abs changing slightly during development. • There are a small group of clones of each type of B-lymphocyte
- 14. B -Lymphocytes • Atthe clone stage antibodies do not leave the B- cells. • The abs are embedded in the plasma membrane of the cell and are called antibody receptors. • When the receptors in the membrane recognise and antigen on the surface of the pathogen the B-cell divides rapidly. • The antigens are presented to the B-cells by macrophages
- 15.
- 16. B -Lymphocytes • Someactivated B cells PLASMA CELLS these produce lots of antibodies, < 1000/sec • The antibodies travel to the blood, lymph, lining of gut and lungs. • The number of plasma cells goes down after a few weeks • Antibodies stay in the blood longer but eventually their numbers go down too.
- 17. B -Lymphocytes • Someactivated B cells MEMORY CELLS. • Memory cells divide rapidly as soon as the antigen is reintroduced. • There are many more memory cells than there were clone cells. • When the pathogen/infection infects again it is destroyed before any symptoms show.
- 19. Antibodies • Also knownas immunoglobulins • Globular glycoproteins • The heavy and light chains are polypeptides • The chains are held together by disulphide bridges • Each ab has 2 identical ag binding sites – variable regions. • The order of amino acids in the variable region determines the shape of the binding site
- 20. How Abs work •Some act as labels to identify antigens for phagocytes • Some work as antitoxins i.e. they block toxins for e.g. those causing diphtheria and tetanus • Some attach to bacterial flagella making them less active and easier for phagocytes to engulf • Some cause agglutination (clumping together) of bacteria making them less likely to spread
- 21.
- 22. Type Number of agbinding sites Site of action Functions IgG 2 •Blood •Tissue fluid •CAN CROSS PLACENTA •Increase macrophage activity •Antitoxins •Agglutination IgM 10 •Blood •Tissue fluid Agglutination IgA 2 or 4 •Secretions (saliva, tears, small intestine, vaginal, prostate, nasal, breast milk) •Stop bacteria adhering to host cells •Prevents bacteria forming colonies on mucous membranes IgE 2 Tissues •Activate mast cells HISTAMINE •Worm response
- 23. T-Lymphocytes • Mature T-cellshave T cell receptors which have a very similar structure to antibodies and are specific to 1 antigen. • They are activated when the receptor comes into contact with the Ag with another host cell (e.g. on a macrophage membrane or an invaded body cell)
- 24. T-Lymphocytes • After activationthe cell divides to form: • T-helper cells – secrete CYTOKINES help B cells divide stimulate macrophages • Cytotoxic T cells (killer T cells) Kill body cells displaying antigen • Memory T cells remain in body • Suppressor T cells
- 27. Active and PassiveImmunity Active immunity Lymphocytes are activated by antigens on the surface of pathogens Natural active immunity - acquired due to infection Artificial active immunity – vaccination Takes time for enough B and T cells to be produced to mount an effective response.
- 28. Active and PassiveImmunity Passive immunity B and T cells are not activated and plasma cells have not produced antibodies. The antigen doesn’t have to be encountered for the body to make the antibodies. Antibodies appear immediately in blood but protection is only temporary.
- 29. Active and PassiveImmunity Artificial passive immunity Used when a very rapid immune response is needed e.g. after infection with tetanus. Human antibodies are injected. In the case of tetanus these are antitoxin antibodies. Antibodies come from blood donors who have recently had the tetanus vaccination. Only provides short term protection as abs destroyed by phagocytes in spleen and liver.
- 30. Active and PassiveImmunity Natural passive immunity A mother’s antibodies pass across the placenta to the foetus and remain for several months. Colostrum (the first breast milk) contains lots of IgA which remain on surface of the baby’s gut wall and pass into blood
- 32. Vaccination A preparation containingantigenic material: • Whole live microorganism • Dead microorganism • Attenuated (harmless) microorganism • Toxoid (harmless form of toxin) • Preparation of harmless ags
- 33. Vaccination • Injection intovein or muscle • Oral
- 34. Vaccination Why aren’t theyalways effective? • Natural infections persist within the body for a long time so the immune system has time to develop an effective response, vaccinations from dead m-os do not do this. • Less effective vaccines need booster injections to stimulate secondary responses
- 35. Vaccination Why aren’t theyalways effective? • Some people don’t respond well/at all to vaccinations • Defective immune systems • Malnutrition particularly protein
- 36. Vaccination Why aren’t theyalways effective? • Antigenic variation caused by mutation • Antigenic drift – small changes (still recognised by memory cells) • Antigenic shift – large changes (no longer recognised)
- 37. Vaccination Why aren’t theyalways effective? • No vaccines against protoctists (malaria and sleeping sickness) • Many stages to Plamodium life cycle with many antigens so vaccinations would have to be effective against all stages (or be effective just against infective stage but given in very small time period).
- 38. Vaccination Why aren’t theyalways effective? • Sleeping sickness – Trypanosoma has a thousand different ags and changes them every 4-5 days
- 39. Vaccination Why aren’t theyalways effective? • Antigenic concealment parasites live inside body cells • Plasmodium – liver and blood cells • Parasitic worms – cover themselves in host proteins • HIV – live inside T-helper cells
- 40. Smallpox Symptoms • Red spotscontaining transparent fluid all over body. • Spots fill with pus • Eyelids swell and become glued together
- 41. Smallpox Mortality • 12-30% died •Survivors often left blind and disfigured with scabs.
- 42. Smallpox Eradication programme • Startedby WHO in 1956 • Aimed to rid world of smallpox by 1977 • Involved vaccination and surveillance • Over 80% of populations at risk of the disease were vaccinated • After any reported case everyone in the household and 30 surrounding households vaccinated – RING VACCINATION
- 43. Smallpox Eradication programme • Lastcase of smallpox reported in Somalia in 1977 • World declared free of smallpox in 1980
- 44. Smallpox Eradication programme –why was it successful? • Variola virus stable -> cheap as everyone used same vaccine • Vaccine made from harmless strain of similar virus (vaccinia) • Vaccine could be used at high temperatures • Easy to identify infected people • Smallpox doesn’t lie dormant in body
- 45. Smallpox Eradication programme –why don’t all work? • Political instability • Poor infrastructure • Unstable m-os
- 46. Measles • Caused byan airborne virus • 9th leading cause of death worldwide • Causes rash and fever • Can have fatal complications • Passive immunity from mothers in infants under 8 months • Now quite a rare disease in developed countries due to vaccination
- 47. Measles • Transmitted easilyin overcrowded, insanitary conditions • Mainly affects malnourished infants with vitamin A deficiencies • Responsible for many cases of childhood blindness and can cause severe brain damage • Herd immunity of 93-95% needed to prevent transmission within a population.
- 48. Allergies • When theimmune system responds to harmless substances • Allergens – antigenic substances which do no real harm • Allergens include house dust, animal skin, pollen, house dust mite and its faeces
- 50. Allergies • Histamine causesblood vessels to widen and become leaky. • Fluid and white blood cells leave capillaries. • The area of leakage becomes hot, red and inflamed
- 51. Asthma • Attacks canoccur at any time • Genes play a role in who develops asthma • Breathing becomes difficult, sufferers experience wheezing, coughing, a tightness about the chest and shortage of breath. • 1/7 children in UK has asthma, number is increasing. • >1000 people die each year from asthma every year in the UK
- 52. Asthma • Airways inasthmatics are always inflamed, during an attack this worsens. • Fluid leaks from blood into airways and goblet cells secrete lots of mucus • Airways can become blocked • Muscles surrounding trachea and bronchioles contract which narrows airways further
- 53. Asthma • Vaccines arebeing developed to make allergic responses less severe • Designed to desensitise people so they do not produce antibodies to allergens • Genetic tests may be used to screen children and then a vaccine could be given to prevent them developing asthma