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Immunology Innate Immunity, Summaries of Biotechnology

Bengaluru Central UniversityBiotechnology

Immunology Innate Immunity - Lines of defences

Typology: Summaries

2022/2023

Uploaded on 12/08/2023

Snegapriya
Snegapriya 🇮🇳

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12/6/2023
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IMMUNOLOGY &Medical BT
Divya Joseph Pereira
ASSISTANT PROFESSOR
JYOTI NIVAS COLLEGE AUTONOMOUS
DEFINITION
•Immunology is the study of the immune system
•It is a very important branch of the medical and biological sciences.
•The immune system protects us from infection through various lines
of defence.
•If the immune system is not functioning as it should, it can result in
disease, such as autoimmunity, allergy and cancer.
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IMMUNOLOGY &Medical BT

Divya Joseph Pereira ASSISTANT PROFESSOR JYOTI NIVAS COLLEGE AUTONOMOUS

DEFINITION

  • Immunology is the study of the immune system
  • It is a very important branch of the medical and biological sciences.
  • The immune system protects us from infection through various lines of defence.
  • If the immune system is not functioning as it should, it can result in disease, such as autoimmunity, allergy and cancer.

WHY IS IMMUNOLOGY IMPORTANT

  • From Edward Jenner’s pioneering work in the 18th^ Century that would ultimately lead to vaccination in its modern form to the many scientific breakthroughs in the 19th^ and 20th^ centuries that would lead to, amongst other things, safe organ transplantation, the identification of blood groups, and the now ubiquitous use of monoclonal antibodies throughout science and healthcare, immunology has changed the face of modern medicine.
  • Immunological research continues to extend horizons in our understanding of how to treat significant health issues, with ongoing research efforts in immunotherapy, autoimmune diseases, and vaccines for emerging pathogens, such as Ebola.
  • Advancing our understanding of basic immunology is essential for clinical and commercial application and has facilitated the discovery of new diagnostics and treatments to manage a wide array of diseases.
  • In addition to the above, coupled with advancing technology, immunological research has provided critically important research techniques and tools, such as flow cytometry and antibody technology.

Branches of Immunology

Molecular immunology - is a branch of immunology that studies the immune system and processes of the immune system at the molecular level. Here, then, molecular immunologists are concerned with such processes as signaling and activation of immune cells as well as the structure and functioning of such molecules as receptors and mediators among others. Cellular immunology - Unlike molecular biology, cellular biology gives focus to the different types of immune cells that can be found in various tissues and organs in the body. These include such cells as the T and B cells. Here, immunologists study the different functions of the cells and how they vary (reproduction, functions etc). This has not only made it possible to determine how different immune cells function, but also classify cells of the immune system based on how they are reproduced, their functions as well as other general characteristics.

First line of Defense

  • SKIN – Physical factors
  • Dermis(inner )
  • Epidermis(outer )
  • Tightly packed epidermis
  • Top layer od epidermis dead
  • &contain protective protein
  • Keratin
  • Top layer shed
  • Dryness of the skin
  • Moist skin infection more
  • Bacteria most likely present staphylococcus

Chemical factors – Skin

  • Sebaceous (oil gland )
  • Sebum – protective film over the skin
  • Contains unsaturated fatty acids – inhibit growth of bacteria &fungi
  • Low pH- 3-5(presence of fatty acids and lactic acid )- acidic
  • Sweat glands produce perspiration , which eliminates certain wastes ,
  • Perspiration contain lysozyme – enzyme which breaks (peptidoglycan)gram positive bacteria & to lesser extent gram negative bacteria.

Mucous membrane

  • Epithelial layer
  • Connective tissue layer
  • Offer lesser protection than skin.
  • Mucous membrane. Lines – gastrointestinal , respiratory , and genitourinary tracts.
  • Epithelial layer of a mucous membrane secretes fluid mucus(slightly viscous glycoprotein produced by gobletcells of a mucous membrane.

Overview Of the immune system – cell components

Blood and it ‘s components

Natural Killer cell

Natural killer cells

  • Are found in blood and in the spleen , lymph nodes , and red bone marrow
  • Have the ability to kill wide variety of infected body cells and certain tumor cells.
  • Attack cells that have unusual plasma membrane proteins
  • Binding of the Nk Cells to an infected cell causes release of granules containing toxic substances.
  • Some granules contain perforin – inserts in to the plasma membrane of the target cell and the cell burst – cytolysis
  • Other granules release – granzymes – which are protein digesting enzymes that induce the target cell to undergo apoptosis or self destruction
  • it Does not kill the pathogen.
  • Pathogen may be killed by a phagocytic cell.

Basophil

  • Granulocyte
  • Stain blue purple
  • Basic dye – Methylene blue
  • Release substances such as histamine that are important for inflammation.
  • Allergic reactions
  • 0.5-1% in the blood

Eosinophil

  • Granulocyte
  • Stain red or orange with acidic stain
  • Somewhat phagocytic
  • Ability to leave the blood
  • Produce toxic proteins against parasites – such as helminths.
  • Although eosinophil are small to ingest and destroy helminths they can attach to the outer surface of the parasites
  • Discharge peroxide ions that destroy them
  • There number increases during parasitic worm infections and allergic reactions
  • 2-4%in the blood

Agranulocytes – Monocyte / Macrophage

  • They have granules but not visible under the light microscope after staining
  • Monocytes are not actively phagocytic – blood
  • But when they leave circulating blood and enter tissue they mature in to macrophages
  • Phagocytosis
  • Dispose worn out blood cells
  • 3-8%

Lymphocytes

  • Natural killer cells
  • Tcells
  • Bcells

Innate Immunity

  • 1 st^ and 2nd^ line of Défense
  • Nonspecific
  • Present at birth
  • Rapid response
  • no memory component
  • Body’s early warning systems and are designed to prevent microbes from gaining access in to the body

Acquired Immunity

  • Other wise called adaptive immunity
  • Specific immunity – specific recognition of the microbe
  • Slow to respond
  • Has memory component
  • Bells and Tcells – contributors

Inflammation

Steps

  1. Tissue damage - Chemicals such as histamine , kinins, prostaglandins- are released by damaged cells - Blood clots forms,
  2. Vasodilation and increased permeability of blood vessels
  • Margination (phagocytes stick to endothelium )
  • Emigration - Phagocytes squeeze between endothelial cells
  1. Phagocytosis of bacteria by phagocytic cells -Neutrophil , Macrophage

Steps involved in phagocytosis

  • Chemotaxis –chemical attraction of phagocytes to the microbe.
  • adherence of microbe –more easy if coated with serum proteins – opsonization.
  • Ingestion of Microbe – plasma mem of the phagocyte extendsprojections called pseudopods.- pseudopods surround and meet and fuse with the microbes
  • Formation of Phagosome 0r phagocytic vesicle- membrane pumps – protons – ph4- hydrolytic enzymes activated.
  • Fusion of the phagosome with the lysosome –( contains digestive enzymes )to form Phagolysosome – 10 – 30 mins to kill all the pathogens
  • Digestion of ingested microbe by enzymes
  • Formation of residual body( indigestible material ) containing indigestible material
  • Discharge of waste materials.

Questions

  • List out the APC ‘s in our body?
  • What is cellular mediated immunity?
  • What is humoral mediated immunity?
  • Enumerate the functions of the granulocytes?
  • What are important steps involved in inflammation?
  • Explain in detail the first and second line of immune system?
  • What are the functions of a natural killer cells?
  • Differentiate between innate and acquired immune system.
  • Granulocyte responsible for clearing parasitic infections.

Fever

Describe its causes and effects

  • Inflammation is a local response of the body to injury.
  • There are systemic and overall Reponses– fever
  • Abnormally high temperature
  • Cause of fever is infection from bacteria or viruses.
  • Body temperature controlled by a part of brain called Hypothalamus.
  • Hypothalamus normally set at 37 degree Celsius.
  • Certain substances affect the hypothalamus--- by setting it at higher temperature.
  • When the phagocytes –ingest bacteria – the LPS(lipopolysaccharides of the cell wall are released .( part of the cell wall )

Fever …..

  • Causes the phagocytes to release interleukin – 1 called endogenous pyrogens
  • Interleukin – 1 causes the hypothalamus to release prostaglandins
  • Reset the hypothalamic thermostat at a higher temperature thereby causing fever.
  • Another cytokine – alpha tumor necrosis factor which is produced by macrophages and mast cells also induce fever.
  • Mast cells and Basophils are the same
  • Mast cells in the tissue and Basophils in the blood.

Antimicrobial substances

  • body produces some – Antimicrobial substances

• Among this the most important is the complement

system and Interferon.

Interferons

  • Are small proteins
  • Molecular weight – 15,000- 30000
  • Resistant to heat
  • Quite stable at low pH
  • Cells infected with virus produce interferons
  • Interferons are host cell specific
  • INF’s

Interferons …..

  • Interferons produced by human cells protect only human cells but doesn’t not protect cells of other species –mice , chickens.
  • there are different types of interferons produced in the same animal
  • INF- ALPHA
  • INF – BETA
  • INF- GAMMA
  • Interferons produced by fibroblasts in connective tissue , lymphocytes and leukocytes.

Actions of interferon

  • IFN- alpha and IFN- beta –produced by virus infected host cells ONLY IN VERY SMALL QUANTITIES.
  • THEY REACT
  • WITH PLASMA OR NUCLEAR MEMBRANE RECEPTORS ---
  • INDUCING THE UNINFECTED CELLS TO MANUFACTURE ----- mRNA
  • For the synthesis of antiviral proteins (AVPs)
  • These proteins are enzymes that disrupt various stages of viral replication.
  • Gamma interferon – produced by lymphocytes – it induces neutrophil and macrophages to kill bacteria.