Download to read offline
More Related Content
Similar to Introduction to Immunology.pptx habib medical School
![opioids Islamic University [Autosaved].ppt](https://cdn.slidesharecdn.com/ss_thumbnails/opioidsautosaved-250821041508-2c49bca5-thumbnail.jpg?width=640&height=640&fit=bounds)
Introduction to Immunology.pptx habib medical School
- 1.
- 2. Content Review of Bacterialanatomy Bacterial pathogenesis and virulence History of immunology (Development & evolution of the field) Role of the immune system in defense • Classification of the immune system
- 3. Review of bacterialmorphology • Two groups a) Cocci (spherical-shaped) b) Bacillus (rod-shaped)
- 4. Review of bacterialmorphology • Coccus are divided into six forms 1) Monococci (e.g. Micrococcus flavus) 2) Cocci in clusters (e.g. staphylococci) 3) Cocci in chains (e.g. streptococci) 4) Cocci in pairs/diplococci (e.g. Neisseria) 5) Cocci in 4s/tetrad (Tetracocci) 6) Cocci cuboidal arrangement (e.g. in Sarcina)
- 5. Review of bacterialmorphology • Rods (Bacilli): • They are divided into eight morphological forms; 1. Straight rods/bacillus e.g. E. coli 2. Coccobacilli e.g Yersinia 3. Diplobacilli e.g. Coxiella burnetii 4. Palisades e.g. Corynebacterium diphtheria 5. Branching rods e.g. Actinomyces 6. Comma shaped/curved rod e.g Vibrios 7. Spore forming rods e.g Clostridium and Bacillus 8. Spiral shaped rods e.g Treponema pallidum & the spirochaetes
- 6. Anatomy of thebacterial cell Prokaryotic cell organization with; Circular DNA No membrane bound organelles No defined nuclear membrane (Transcription and translation can occur simultaneously) DNA is haploid 70s ribosomes
- 7. Anatomy of thebacterial cell • Three architectural regions of the bacterial cell a) Appendages (Flagella and Pilli/fimbriae): contribute to antigenicity b) A cell envelope (capsule, cell wall and plasma membrane): contribute to the antigenicity c) Cytoplasmic region (circular DNA, ribosomes, mesosome and inclusion bodies)
- 8. The cell wall •Essential structure for viability (Overcoming osmotic bursting) • Chemically unique components only to bacteria are present • They are key sites for antibiotic attack • Posses ligands for adherence on to the host cells • Contribute to immunological/antigenic variations among bacteria
- 9. The cell wall •Made of a polysaccharide murein or peptidoglycan layer • The peptidoglycan is a polymer of sugars (glycan) cross-linked by short chains of amino acids (peptides) • The peptidoglycan also contain N-acetyl muramic acid
- 10. The cell wall •In the Gram positive bacteria; a) There are several layers of peptidoglycan making the cell wall thick b) The peptidoglycan layers are cross linked by groups of molecules called lipoteichoic acid (LTA)
- 11. The cell wall •In Gram negative bacteria, a) The cell wall has a single layer of peptidoglycan making the cell wall thin b) The lipoteichoic acids (LTAs) are absent c) The peptidoglycan layer is surrounded by a membranous structure called the outer membrane/lipopolysaccharide d) The Lipopolysaccharide (LPS) is a virulence factor which is toxic to hosts (endotoxin)
- 12. The capsule andslime layers • A true capsule is a discrete detectable layer of polysaccharide out side the cell wall • The slime layer /biofilm is a less discrete polysaccharide layer out side the cell • The true capsule is demonstrated by Indian ink staining
- 13. Functions of capsulesand slime layers • Both are virulence factors as they allow for adherence on the host cell surface . • As virulence factors; 1. they cause resistance to phagocytosis 2. they cause resistance to intra-cellular killing by macrophages and PMNLs 3. they resist attack by antibodies 4. they resist opsonization
- 14. The cytoplasm • Keycomponents of the cytoplasm include; • Circular DNA/ Prokaryotic chromosome • Ribosomes (70s) • Enzymes/proteins • Plasmid-Extrachromosomal DNA:- mediates antibiotic resistance • Mesosome (for respiration) • Inclusion bodies like food particles
- 15. Cell surface structures Flagella: •used for locomotion and is a virulence factor Pilli: • Sex Pilli: Mediate DNA transfer during sexual reproduction/conjugation • Common Pilli/Fimbriae: Attachment on to surfaces, resistance to phagocytosis
- 16. Flagella • Four basictypes a) Monotrichous: one flagellum at one end e.g. in Vibrio b) Lophotrichous: Many flagella at one end e.g Bartonella c) Peritrichous: Many flagella all over the cell e.g in E coli d) Amphitrichous: Many/one flagellum at both ends e.g Spirohaetes
- 17. Pathogenesis and virulence •A pathogen: disease causing organism • Pathogenicity: the ability to cause disease • Virulence: the degree of pathogenicity • Pathogenesis: the process of disease development (prognosis)
- 18. Pathogenesis and virulence Mechanismof bacterial pathogenicity • Invasiveness: • Encompasses: ability to invade tissue, adhere, multiply, production of enzymes that facilitate invasion and ability to evade the host’s immune system • Toxigenesis: ability to produce toxins • Exotoxins produced by bacterial cells and can act away from the site of bacterial growth • Endotoxins; Cell associated toxins (LPS)
- 19. Pathogenesis and virulence •Bacterial adherence to Mucosal surfaces • The first step in virulence is adhesion • The following molecules are use in bacterial adherence • Adhesin: macro molecules that bind bacteria to any surface • Receptors: Complementary macromolecules on the host cells to which bacteria can bind • Fimbriae • Common pili • Capsule • Slime layer/biofilms • LPS • Teichoic acids
- 20. Pathogenesis and virulence Enzymesinvolved in invasion by bacteria • Collagenases. E.g in C. perfringens break down collagen allowing tissue invasion • Neuraminidase. • Produced by Enterobacteriaceae e.g. Shigella dysenteriae. • Destroys muramic acid which cements epithelial cells of intestinal mucosa • Streptokinase and staphylokinase: • prevent formation of fibrin clot which would other wise limit colonization of tissue by streptococci and staphylococci • Heamolysins/leucocidins; hemolyze RBCs and WBCs • Phospholipases: Destroy phospholipids in cell membrane • Hyaluronidase: Destroy hyaluronic acid of connective tissue
- 21. History of immunology(Development & evolution of the field) • Immunology is defined as the study of the molecules, cells, organs, and systems responsible for the recognition and disposal of foreign material . • Immunology began as a branch of microbiology. • The study of infectious disease and the body’s response to them has a major role for the development of immunology. • The concept of germ theory of disease has contributed to the field of immunology.
- 22. History of immunology(Development & evolution of the field) • The germ theory of disease (Louis Pasteur) • Every disease to occur, there must be a causative agent • This was a break through in medicine and improved the health of people.
- 23. History of immunology(Development & evolution of the field) Koch’s postulates • Evolved from the germ theory 1. For every disease there must be a causative agent 2. The agent must be isolated and cultured in vitro 3. The agent must be re-produced when inoculated in a susceptible host 4. The agent must be isolated from the animal where it is inoculated
- 24. History of immunology(Development & evolution of the field) Edward Jenner and the concept of immunization • He observed that dairy maids who had naturally contracted a mild infection called cowpox seemed to be protected against smallpox • Small pox was a horribly disfiguring disease and a major killer of the time
- 25. History of immunology(Development & evolution of the field) • In 1796, Jenner inoculated an eight year-old boy with fluid from cowpox blisters on the hand of a dairymaid • The boy contracted cowpox. • Then two month later Jenner inoculated him with fluid from a small pox blister, the boy only developed a mild small pox disease. • His exposure to cowpox had made him immune to the small pox infection. • Starting with these crude methods, the science of immunization/ vaccination was born that has saved lives of many up-to-date. .
- 26. History of immunology(Development & evolution of the field) • In 1879, the first human pathogen, gonococcus, was isolated by Neisser. • In 1883, Klebs and co-workers isolated diphtheria bacilli • In 1888, Yersin discovered the diphtheria toxin • This led to the discovery of toxoid vaccines • In 1888, the first antibodies, were reported by Pasteur • The antibodies guided the design of vaccines
- 27. History of immunology(Development & evolution of the field) • In 1900, Karl Landsteiner discovered the ABO blood group antigens and their corresponding antibodies • This led to the ability to transfuse blood with out provoking immune reactions • This introduced the immunological error
- 28. History of immunology(Development & evolution of the field) • In 1939, Philip Levine described a case of post transfusion hemolysis in blood group O woman who received blood from her blood group O husband • It was later discovered that the reaction was due to Rhesus incompatibility following discoveries by Landsteiner in 1940
- 29. Role of immunesystem in defense • The role of our immune system is to distinguish between self and non self antigens and deal with the none self. • The ability to identify the self antigens and protecting them from attack by our immune system is called self tolerance • However, some times our immune system fails to identify some antigens as self and thus destroys them. • This is called lack of self tolerance • This leads to auto-immune disease like Juvenile DM, many forms of arthritis etc
- 30. Classification of theimmune system Immunity is classified into two major groups: - Non specific immunity - Specific immunity
- 31. Classification of theimmune system Non specific (natural or innate) immunity. • Non-specific immunity, also called natural or innate immunity, is the first line of defense against any infectious agent. • Non specific host responses provide an effective barrier that prevents the microorganisms; • from penetrating, • destroy the invader if it gains access to the tissues
- 32. Classification of theimmune system • Several natural mechanisms are available in the immunocompetent host. • These include; 1. physical or mechanical barrier, 2. biochemical factors, 3. cellular mechanism, 4. role of normal flora 5. inflammatory reactions.
- 33. Classification of theimmune system 1. Physical or mechanical barrier a) The skin • The unbroken skin and mucus membrane are effective mechanical barriers to infectious agents • The surface of the skin is also inhibitory to the growth of most microorganisms because of ; • low moisture • low pH
- 34. Classification of theimmune system b) The Mucus membrane • They consist of an epithelial layer and an underlying connective tissue layer. • They line the entire digestive, respiratory, urinary, and reproductive tracts. • For example, the epithelial surface that lines the nasal cavity and throat secrete mucus which traps pathogens in the cilia of the lining epithelium • The action of coughing removes mucus that contains microorganisms. • In the urethra rapid flow of urine washes away most microorganisms. • Tear that wash the conjunctiva perform a similar defensive function.
- 35. Classification of theimmune system 2. Biochemical factors • These are chemical secretions produced by the body that inhibit microbial growth. • For example; • keratin is a skin protein produced by the outer most cells of the skin making dry preventing microbial colonization • hydrochloric acid and bile salt, which are secreted by the stomach and liver have intolerable PH by microorganisms • lysozyme is an enzyme found in many body fluids and secretions such as tears can break down the cell wall of Gram-positive bacteria • Complement is a family of more than twenty different proteins in serum that function as a non- specific defense against infection • Interferons are small proteins produced by eucaryotic cells in response to viral infection.
- 36. Classification of theimmune system 3. Cellular mechanism • Alveolar macrophages remove particles and organisms that enter the alveoli. • Kupffer cells are liver macrophages that destroy pathogens that enter the liver • Microglia are nerve tissue macrophages that destroy pathogens in the nervous tissue • Neutrophils are the first phagocytes in the infected area that can non-specifically phagocytize some microbes • Natural killer cells are large lymphocytes whose function is to kill undesirable cells such as tumor cells and virus infected cells.
- 37. Classification of theimmune system 4. Role of normal flora • These commensals can stop the growth of potentially pathogenic organisms through different mechanism such by producing substance against pathogenic organism. Examples • Staphylococcus • Micrococcus • Dermabacter Are all normal flora on the skin and prevent colonization of pathogenic bacteria on the skin
- 38. Classification of theimmune system 5. Inflammatory reactions • The inflammatory response refer to vascular and cellular response to the presence of invading microorganisms or injury • The process of inflammation may be divided in to the following stages: • Initiation (Damage to tissue) • Tissue response: release of chemical factors such histamine, • Leukocyte response: engulfing the microbes and damaged tissue • Tissue repair (resolution) • Cure.
- 39. Classification of theimmune system Specific immunity • also called acquired or adaptive immunity, is a defense system that allows the body to recognize, remember, and respond to a specific antigen previously exposed to • Specific immunity can result in the recovery from disease while leaving the host with specific immunologic memory. • memory or recall allows the host to respond more effectively if reinfection with the same microorganism occurs.
- 40. Classification of theimmune system Specific immunity • Because of acquired immunity, we usually suffer from many diseases only once, for example measles, mumps etc. • Specific immunity can be active or passive, and each of these types can in turn be naturally or artificially acquired.
- 41. Classification of theimmune system Passive immunity • It is an immunity in which antibodies produced elsewhere are given to the individual • They are divided into two a) Naturally acquired passive immunity: • refers to antibodies transferred from mother to fetus across the placenta and to the newborn in colostrums and breast milk during the first few months of life. b) Artificially acquired passive immunity: • is introduction of antibodies that are formed by an animal or a human to an individual to prevent or treat infection.
- 42. Classification of theimmune system Active immunity • It is a product of the individual’s own immune system in response to a foreign antigen. a)Naturally acquired active immunity: • is immunity that comes from infections encountered in daily life. b) Artificially acquired active immunity: • is stimulated by initial exposure to specific foreign macromolecules through the use of vaccines to artificially establish a state of immunity.
- 43. Factors Associated Immunity a)Age. • Young children and old people tend to be easily infected or suffer more serious infections e.g. babies under 2 years have little immunity to Haemophilus influenza type B and Neisseria meningitidis • In older people, the aging processes, chronic ill health e.t.c. contributes to less active immunity b) Malnutrition and under nutrition. • Protein deficiency leads to low immunoglobulin and complement levels and poor T-cell function c) Pregnancy. • There is a lowering of immunity in pregnancy. This increases the risk of microbial infections especially in poorly malnourished mothers.
- 44. Factors Associated Immunity d)Existing diseases. Many bacterial, viral and parasitic infections affect the immunity leading to reduced protection to other diseases. e) Genetic factors The possession of certain genes is linked to immune disorders. These include genes that lead to a deficiency in protection of B and T-lymphocytes. f) Drugs Certain drugs such as these used to treat malignant conditions show toxicity not just to malignant cells but also to normal cells including those involved in immunity. They prevent cells multiplying and therefore reduce the immune responses, leading to opportunistic infections and also to reactivation of latent viruses.
- 45. Exercise Define the following a)Sterile immunity b) Incomplete immunity. c) Concomitant immunity: d) Partial immunity e) Latent infection f) Hard immunity
- 46.