Introduction to immune system

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  • While still an apothecary's apprentice in the late 1760s, Jenner had been intrigued by possible relationships between smallpox, cowpox, and swinepox. At the time, he was ridiculed. By 1780, however, he returned to the idea, and in 1789 he experimented by inoculating his own son, then aged one-and-a-half, with the swine pox, followed by conventional smallpox inoculation. Jenner's Inquiry, first published in 1798, reported how, over a period of years, he had noticed the immunity provided by cow-pox, and how he decided deliberately to introduce the disease into a patient to see if the effect could be artificially produced. Soon afterwards, he would again inoculate his patients, this time with live smallpox virus ("variolation"), to see if the cow-pox had worked. The "healthy boy" whom Jenner, on May 14 1796, first vaccinated with virus from the dairymaid Sarah Nelmes was James Phipps, who proved Jenner's point by surviving repeated unsuccessful attempts to infect him with smallpox. On May 14, 1796, a milkmaid named Sarah Nelmes visited Dr. Jenner for the treatment of Cowpox. Dr. Jenner decided it was time to test his vaccination, and he tested it on his gardener's son, an eight-year-old boy named James Phipps. (He got the term "vacca" from the Latin word for "cow.") The boy did contract Cowpox, but he recovered from it within a few days. Dr. Jenner then waited eight weeks for the boy's body to build an immunity. To complete his experiment, Dr. Jenner exposed James to Smallopx. Amazingly, the boy did not contract the deadly disease, and the doctor claimed success.
  • Lots left to learn. More funds are needed to understand and combat pathogens such as (clockwise from top left) coronavirus, Borrelia burgdorferi , HIV, and Plasmodium malariae . image credit: CDC


  • 1. INTRODUCTION TO IMMUNE SYSTEMINTRODUCTION TO IMMUNE SYSTEM PRESENTER Shakira Ghazanfar PhDScholar 24-2-2013 ‫الرحيم‬ ‫الرحمن‬ ‫اللة‬ ‫بسم‬‫الرحيم‬ ‫الرحمن‬ ‫اللة‬ ‫بسم‬
  • 2. INTRODUCTIONINTRODUCTION • Immunity : Defence capacity of the body to combat diseases  counter infection. Immune System: Molecules, cells, tissues and organs which provide non- specific and specific protection against, Microorganisms, Microbial toxins, Tumor cells.
  • 3. The Immune SystemThe Immune System 3 Major Functions3 Major Functions 1.1. Protection from disease causing invadersProtection from disease causing invaders 2.2. Removal of dead /damaged tissues &Removal of dead /damaged tissues & cellscells 3.3. Recognition & removal of abnormal cellsRecognition & removal of abnormal cells
  • 4. Types Of Immunity • Inborn or innate immunity: It is present at birth; This is our First Line Of Defense. • Acquired or specific: It is not present at birth but becomes part of our immune system as the lymphoid system develops. • 1970: WHO defined immunity as immune response to antigen ( Foreign body) in form of • Humoral ( activation of B-lymhocytes) • Cellular (by activation of T-lymphocytes
  • 5. Cells Involved in Immunity • Macrophages • B cells • T cells
  • 6. Innate Immunity
  • 7. Innate Immunity Defensive mechanisms include : 1) Innate immunity (Natural or Non specific) 2) Acquired immunity (Adaptive or Specific) Cell-mediated immunity Humoral immunity
  • 8. Component of Innate Immunity Innate Immune system First line Second line 1) Mechanical barriers A- cells 2) Chemical & biochemical inhibitors 1- Natural killer 3) Normal flora 2- Phagocytes B- Soluble factors C- Inflammatory barriers
  • 9. Important components of innate immunity Factors that limit entry of microorganisms into the body Factor Mode Of Action -Keratin layer of intact skin -Acts as mechanical barrier -Lysozyme in tears and other secretions -Degrades peptidoglycan in bacteria cell wall -Respiratory cilia -Elevate mucus containing trapped organisms -Low pH in stomach and vagina; -Retards growth of microbes fatty acids in skin -Surface phagocytes -Ingest and destroy microbes (eg. alveolar macrophages) -Defensins (cationic peptides) -Create pores in microbial membrane -Normal flora of throat, colon -Occupy receptors which prevent and vagina colonization by pathogens
  • 10. Important components of innate immunity Factors that limit growth of microorganisms within the body • Natural killer cells • Neutrophils • Macrophages and dendritic cells • Inferons • Complement • Transferrin and lactoferrin • Fever • Inflammatory response • APOBEC3G (apolypoprotein is RNA editing enzyme) • Kill virus infected cells • Ingest and destroy microbes • Ingest and destroy microbes, and present antigen to helper T-cells • Inhibit viral replication • C3b is an opsonin, membrane attack complex creates holes in bacterial membranes • Sequester iron required for bacterial growth • Elevated temperature retards bacterial growth • Limits spread of microbes • Causes hypermutation in retroviral DNA and mRNA
  • 11. Macrophages and other antigen presenting cells such as dendritic cells, participate in both the innate arm and acquired arm of the immune system. They are in effect a bridge between the two arms. As part of the innate arm they ingest and kill various microbes. They also present antigens to helper T cells which is the essential first step in the activation of the acquired arm.
  • 12. Main Components of Innate Immunity that contribute to humoral ( antibody-mediated ) immunity and cell mediated immunity Innate Humoral Immunity Cell mediated Immunity Complement Neutrophil Macrophages Natural killer cells
  • 13. Specificity Of The Immune Response -Recognition of the foreign organisms by specific immune cells -Activation of these immune cells to produce a specific response (eg,antibodies) -Response that specifically targets the organisms for destruction
  • 14. Major Functions Of T Cells and B cells Antibody-Mediated Immunity (B Cells) 1) Host defense against infection 2) (Opsonize bacteria, neutralize toxins and viruses) 3) Allergy (hypersensitivity) eg, hay fever anaphylactic shock 4) Autoimmunity Cell Mediated Immunity 1) Host defense against infection (especially M.tuberculosis, fungi and virus infected cells) 2) Allergy (hypersensitivity )eg poison oak 3) Graft and tumor rejection 4) Regulation of antibody response (help and suppression)
  • 15. Important features Of Innate Immunity Specificity Effective immediately Improves Has after exposure to After Exposure memory microbe Nonspecific Yes in No No minutes
  • 16. Active and Passive Immunity • Active immunity is resistance acquired after contact with foreign antigens, eg, microorganisims • This contact may consist of : Clinical or subclinical infections • Immunization with live or killed infectious agents or their antigens. • Exposure to microbial products (eg, toxins and toxoids)
  • 17. Immunogen and Antigen • When foreign substances (Ag) are introduced into the body, they lead to anti-foreign substance • ( Anti-body ) formation • Immunogenic when they are able to produce specific immune response; that they will stimulate immune cells and then give rise to immunological reaction (Humoral or cellular). • Antigenic substances cannot directly yield immune response, but need some help by some proteins) and then • They can react with antibodies. • All immunogens are antigenic but not all antigens are immunogenic
  • 18. Hapten • Hapten is a greek word meaning to fasten. These are partial antigens. These are not immunogenic. • Hapten needs carrier proteins like albumin, globulin and synthetic polypeptide to become immunogenic. • Hapten (Hp)+Carrier Protein (Cp) Hp+Cp-Ab formation against hapten • Antibiotics, analgesics, penicilin and alpha- methyldopa • Therefore haptens are antigenic and not immunogenic
  • 19. Thank you