Download Free Medical Introduction to the immune system PowerPoint Presentation

Introduction to the immune system PowerPoint Presentation

DOWNLOAD MEDICAL POWERPOINT PRESENTATION

About This Presentation

Description : Check out this medical presentation on Influenza (Flu), which is titled "Introduction to the immune system", to know about our immune system.

Tags : Influenza, Flu, Introduction, immune system

Published on : Aug 29, 2021 | Views : 2128 | Downloads : 44

Shareable Url :

Embed Code :

Comment

Transcript

Slide 1-

Introduction to the immune system Vivekanandan Perumal vperumal@bioschool.iitd.ac.in 011-26597532 Office hours Wednesday and Friday 5-6pm
Slide 2-

Immunity Immunity is body's ability to resist or eliminate potentially harmful foreign materials or abnormal cells
Slide 3-

History: what imparts Immunity? Emil von Behring and Kitasato (1890) Serum from vaccinated animals was protective (diptheria) Metchinkoff (1880) Cell based Immunity Merrill Chase (1940)- Transfer of WBC (immunity to tuberculosis) Both serum and cells contribute to immunity
Slide 4-

Immunology- nobel prizes Since 1901 there have been 19 Nobel Prizes for immunology-related research.
Slide 5-

The immune system A functional system – NOT an organ system: Complex system – includes Skin – physical barrier Lining of mucus membranes – physical barrier Secretions – tears, mucus etc - antimicrobial Blood cells and vasculature – WBCs Bone marrow Liver – makes complement proteins Lymphatic system and lymphoid organs Most tissues – have resident immune cells
Slide 6-

Immunity Immunity (immunis- Latin-exempt, state of protection from infectious diseases) Immunity is body's ability to resist or eliminate potentially harmful foreign materials or abnormal cells consists of following activities: Defense against invading pathogens (viruses & bacteria) Removal of 'worn-out' cells (e.g., old RBCs) & tissue debris (e.g., from injury or disease) Identification & destruction of abnormal or mutant cells (primary defense against cancer) Rejection of 'foreign' cells (e.g., organ transplant) Inappropriate responses: Allergies - response to normally harmless substances Autoimmune diseases
Slide 7-

The Immune System
Slide 8-

Overview of the Immune System Interactions between the two systems
Slide 9-

A typical immune response Complement
Slide 10-

Innate immunity vs Adaptive Immunity No memory No time lag Not antigen specific A lag period Antigen specific Development of memory Innate Immunity (first line of defense) Adaptive Immunity (second line of defense)
Slide 11-

The innate immune System Interactions between the two systems
Slide 12-

Innate immune system External defenses
Slide 13-

Anatomical Barriers - Mechanical Factors Skin Flushing action of saliva, tears, urine Mucociliary escalator
Slide 14-

Anatomical Barriers – Chemical factors Antimicrobial Peptides in sweat Lysozyme in tears /saliva HCl in stomach
Slide 15-

Anatomical Barriers – Biological factors Normal flora – microbes in many parts of the body Normal flora – competes with pathogens for nutrients and space Normal flora – > 1000 species of bacteria
Slide 16-

Innate immune system internal defenses
Slide 17-

Innate immune system: components of Blood Complement proteins Coagulation proteins Cytokines WBCs Extracellular
Slide 18-

White blood cells (WBCs) Macrophages B-lymphocytes T-lymphocytes Natural killer(NK) cells Mast cells
Slide 19-

Neutrophils in innate immune response Most abundant WBCs (~50-60%) Efficient phagocytes Most important cells of the innate immune system
Slide 20-

Phagocytosis Phago = to eat Cyte = cell WBCs (eg. Neutrophils) – find, eat and digest microbes !
Slide 21-

How do neutrophils find microbes ? https://youtu.be/I_xh-bkiv_c https://www.youtube.com/watch?v=ZUUfdP87Ssg
Slide 22-

How do neutrophils eat and digest microbes ? Granules
Slide 23-

What’s in the granules ? Lysozyme – digests bacterial cell wall; other antimicrobial proteins
Slide 24-

Additional role of neutrophils Triggers inflammatory response
Slide 25-

Monocytes Monocytes (~5% of WBCs) Migrate into the tissues and become Macrophages Lung Bone Liver Brain intestine
Slide 26-

Macrophages “Big eaters” Phagocytosis of microbes in tissue (neutrophils are present only in blood) Antigen presentation
Slide 27-

Natural killer cells Not B-lymphocytes / T-lymphocytes Important part of the innate immune system Kill virus /bacteria infected cells (Intracellular pathogens) Kills cancer cells
Slide 28-

NK cells differentiate choose cells to kill ? Uninfected cell / Normal cell Microbe infected cell / cancer cell Some cell surface proteins are missing
Slide 29-

How does the killer kill ? Kills both host cells and microbes Release of granules with perforins and proteases
Slide 30-

Toll-like receptors (TLRs) Transmembrane proteins Present on macrophages / few other cells Conserved across vertebrates Important part of innate immune system
Slide 31-

TLRs – What do they do ? They look out for microbes (or their components) They bind to the microbes (or their components) They trigger a cascade of events to kill or protect against pathogens THEY ARE INNATE IMMUNE SENSORS
Slide 32-

TLRs – look out for microbes
Slide 33-

TLRs – bind to microbes / components of microbes
Slide 34-

Which microbial components are recognized by TLRs ?
Slide 35-

What happens when a TLR bind to a microbe ? TLR binding to microbe Inflammation Secretion of Cytokines / Interferon Phagocytosis of infected cell Apoptosis of infected cell Enhanced immune response Killing of infected cell
Slide 36-

Summary: innate response – internal defenses – Cellular (WBCs) Come into play when the external defenses are breached Neutrophils Monocytes /macrophages NK cells TLRs
Slide 37-

Innate immune system: components of Blood Complement proteins Coagulation proteins Cytokines WBCs
Slide 38-

Cytokines Small proteins – secreted by cells of the immune system Affect the behaviour of other cells signalling molecules Key players in innate and acquired immunity
Slide 39-

Which cells release cytokines ? Cells of the immune system: Neutrophils – when they encounter a pathogen Macrophages – when they encounter a pathogen TLRs – bind to microbe / components of a microbe NK cells – on encountering a microbe infected cell /tumour cell Lymphocytes – when they are activated
Slide 40-

Examples of cytokines Interferons Interleukins Tumour necrosis factor (TNF)
Slide 41-

Interferons (IFN) Signalling proteins produced by by virus infected monocytes and lymphocytes Secreted proteins – Key anti-viral proteins “Interfere” with virus replication Warn the neighbouring cells that a virus is around... If we did not have IFNs – most of us may die of influenza virus infection
Slide 42-

42 How does IFN warn the neighbouring cells ?
Slide 43-

43 The infected cells release IFN antiviral state antiviral state antiviral state antiviral state
Slide 44-

44 Virus infects the neighbouring cells antiviral state antiviral state antiviral state antiviral state
Slide 45-

45 Prewarned cells are able to quickly inhibit the virus antiviral state antiviral state antiviral state antiviral state
Slide 46-

How do interferons inhibit viruses ? Host protein Induction Cascade of events Virus ds-RNA Activation Inactive host protein Active host protein Inhibition of host protein synthesis Virus cannot replicate
Slide 47-

Interleukins Interleukins – 1-37 Not stored inside cells Quickly synthesized and secreted in response to infection Key modulators of behaviour of immune cells Mostly secreted by T-lymphocytes & macrophages
Slide 48-

What to interleukins do ? Interleukins Proliferation of immune cells Activation of immune cells Increase antibody production Inflammation
Slide 49-

Tumour necrosis factor (TNF) TNF Killing of cancer Fever Inflammation
Slide 50-

Complement (C`) a large number of distinct plasma proteins that react with one another (C1 thro’ C9) Complement can bind to microbes and coat the microbes Essential part of innate immune response Enhances adaptive immune resposne (taught later)
Slide 51-

Complement proteins: role in innate immune system C`proteins Inflammation Facilitates phagocytosis Direct lysis of pathogens
Slide 52-

How do C` proteins facilitate phagocystosis ? Bacteria coated with C` Neutrophils have C` receptors Initiation of phagocytosis
Slide 53-

How do C` proteins lyse pathogens? Membrane attack complex formed by c` proteins
Slide 54-

Coagulation proteins Coagulation: mechanism to stop bleeding after injury to blood vessels Complex pathway involves Platelets Coagulation factors Vitamin K
Slide 55-

How does blood clot ?
Slide 56-

Coagulation: Delicate balance Coagulation proteins Anticoagulants Blood clotting Inflammation Apoptosis (prog. Cell death) Prevent blood clotting Inhibit inflammation Inhibit apoptosis Too much of clotting – Problem Too little clotting - Problem Maintenance of a balance
Slide 57-

Coagulation and innate immunity Coagulation proteins Anticoagulants Pathogens and cytokines Increased inflammation and increased apoptosis of infected cells
Slide 58-

Summary: what happens when external defenses fail ? Complement
Slide 59-

Summary: innate response – internal defenses Cellular Neutrophils Monocytes /macrophages NK cells TLRs Extracellular Cytokines Complement Coagulation
Slide 60-

Introduction to the immune system Vivekanandan Perumal vperumal@bioschool.iitd.ac.in 011-26597532 Office hours Wednesday and Friday 5-6pm
Slide 61-

Immunology: lecture 3 Inflammation Antigens Antibody
Slide 62-

Inflammation Complex biological process by which body responds to pathogens and irritants Associated with swelling of tissue Key player in innate immune repsone
Slide 63-

All roads lead to inflammation Inflammation Neutrophils Monocytes /macrophages NK cells TLRs Cytokines /IFN C` proteins Coagulation proteins Cellular Extracellular
Slide 64-

Inflammation and vascular changes Vasodilatation Increased capillary permeability Normal blood vessel Dilated blood vessel Normal blood vessel Leaky blood vessel
Slide 65-

Signs of inflammation Vascular changes Vasodilatation Capillary permeability Heat / redness Temporary loss of function Fever Swelling Pain
Slide 66-

Signs of inflammation
Slide 67-

Inflammation and innate immunity Mast cells – similar to basophils in blood; mast cells are present in tissues and release histamines in response to wound / infection /irritant Histamine Pathogen removal Adaptive immune response + + +
Slide 68-

Summary: role of Inflammation in innate immunity Initiation of phagocytosis – killing of pathogen Limiting the spread of infection Stimulate adaptive immune response Initiate tissue repair
Slide 69-

Not everything about Inflammation is good
Slide 70-

The good and bad about inflammation Acute /short-term -Good chronic /long-term - Bad
Slide 71-

Chronic inflammation = tissue damage Chronic inflammation - macrophages in the injured tissue. Macrophages release toxins (including reactive oxygen species or ROS) that injure tissues chronic inflammation is almost always accompanied by tissue destruction. Normal tissue Tissue : chronic inflammation
Slide 72-

Chronic inflammation and tissue damage Reduced tissue function Tissue damage Chronic inflammation Activation of immune cells Killing of host cells
Slide 73-

Chronic inflammation and Cancer ROS O2- OH- DNA Mutation Cancer
Slide 74-

Immunogens / Antigens
Slide 75-

Immunogens and antigens Immunogen / antigen: a substance that elicits an immune response [i.e. a humoral (antibody response) or cell-mediated immune response] Immune response generator Though the two terms are used interchangeably – there are differences between the two
Slide 76-

Epitope Epitope: the portion of an antigen that is recognized and bound by an antibody (Ab) or a T-cell receptor (TCR) epitope = antigenic determinant
Slide 77-

Epitopes Epitope: the portion of an antigen that is recognized and bound by an Ab or a T Cell receptor One protein may have multiple antigenic determinant
Slide 78-

Epitopes B-cell Epitopes – recognized by B-cells T-cell Epitopes – recognized by T cells
Slide 79-

Immunogenicity Immunogencity: is the ability to induce a humoral (antibody) and/or cell-mediated immune response. Weak immunogens Strong immunogens
Slide 80-

What determines immunogenicity ? Foreignness: essential for immunogenicity (self-responsive immune cells are eliminated during lymphocyte development) Size: Bigger>Smaller Chemical composition: Proteins > nucleic acids / polysaccharides / lipids Structure: Primary /secondary /tertiary structures play a role Physical form: Particulate> Soluble
Slide 81-

Host factors affecting immunogencity Difference across species (interspecies) Differences within a species (intraspecies) - Responders / non-responders to vaccine - differences in disease severity in epidemics Genetics Age
Slide 82-

Isoantigens Isoantigens: Antigens present in some but not all members of a species Blood group antigens – basis of blood grouping MHC (major histocompatibility complex)- cell surface glycoproteins
Slide 83-

Autoantigens Autoantigens are substances capable of immunizing the host from which they are obtained. Self antigens are ordinarily non-antigenic Modifications of self-antigens are capable of eliciting an immune response
Slide 84-

Haptens Haptens are small molecules which are non-immunogenic, thus could never induce an immune response by themselves.
Slide 85-

Examples of haptens DO NOT ELICIT an immune response by themselves
Slide 86-

Immunogens / Antigens
Slide 87-

What is an antibody? Produced by Plasma cell (B-lymphocytes producing Ab) Essential part of adaptive immunity Specifically bind a unique antigenic epitope (also called an antigenic determinant) Possesses antigen binding sites Members of the class of proteins called immunoglobulins
Slide 88-

What does an antibody look like ? 2 identical heavy chains 2 identical light chains Each heavy chain – has a constant and a variable region Each light chain has a constant and a variable region H H L L Constant region Variable region
Slide 89-

Antibody: structure and function Fab – fragment antigen binding Fc- Fragment constant
Slide 90-

Antibody: Fab Fab region Variable region of the antibody Tip of the antibody Binds the antigen Specificity of antigen binding determined by VH and VL
Slide 91-

Antibody: Fc Fc region Constant region Base of the antibody Can bind cell receptors and complement proteins
Slide 92-

Antibodies occur in 2 forms Soluble Ag: secreted in blood and tissue Membrane-bound Ag: found on surface of B-cell, also known as a B-cell receptor (BCR) Antibodies exist in two forms