Lecture 21: Immunology Flashcards
what is immunology
Branch of biomedical science that deals with the study of the immune system
what does immunology include
-Cell-mediated immunity
-Humoral immunity
-Immune responses
what is immunity and its two intrinsic systems
-Ability to resist a particular disease and infection
-Immune system consist of two intrinsic systems: innate & adaptive
what is innate immunity
innate (nonspecific resistance) defense system (immunity)
-Constitutes first and second lines of defense
-First line of defense: external body membranes (skin and mucosae)
-Second line of defense: antimicrobial proteins, phagocytes, and other cells (inhibit spread of invaders; inflammation most important mechanism)
what is adaptive immunity
adaptive (specific immunity) defense system (immunity)
-Third line of defense: attacks particular foreign substances (takes longer to react than innate)
-Involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance
-Adjusts to fight against specific microbes
describe the immune system
-Immune system is a functional system rather than organ system
-Innate and adaptive defenses are intertwined:
*Both release and recognize many of the same defensive molecules
*Innate responses release proteins that alert cells of adaptive system to foreign molecules
*Innate defenses do have specific pathways for certain substances
innate immunity and the immune system
-a variety of responses that protect the body against invasion by a wide variety of pathogens and thier toxins
-two lines of denfense: 1. skin and mucous membranes. 2. internal defenses (phagocytes, natural killer cells, inflammation, antimicrobial protains, fever)
how does intact skin epidermis impact immunity
forms mechanical barrier that prevents entry of pathogens and toher harmful substances into body
(has acid mantle on skin & keratin)
how does acid mantle of skin impact immunity
skin secretions (sweat & sebum) make epidermal surface acidic, which inhibits bacterial growth; also contain various bactericidal chemicals
how does keratin impact immunity
provides resistance against acids, alkalis, and bacterial enzymes
how does intact mucous membranes impact immunity
form mechanical barrier that prevents entry of pathogens
(has mucus, nasal hairs, cilia, gastric juice, acid mantle of vagina, lacrimal secretion (tears), saliva, urine)
how does mucus impact immunity
traps microorganisms in respiratory and digestive tracts
how do nasal hairs impact immunity
filter and trap microorganisms in nasal passages
how does cilia impact immunity
propel debris-laden mucus away from nasal cavity and lower respiratory passages
how does gastric juice impact immunity
contains concentrated hydochloric acid and protein-digesting enzymes that destroy pathogens in stomach
how does acid mantle of vagina impact immunity
inhibits growth of most bacteria and fungi
how does lacrimal secretion (sweat) and saliva impact immunity
continuously lubricate and cleanse eyes (tears) and oral cavity (saliva); contain lysozyme and enzyme that destroys microorganisms
how does urine impact immunity
normally acid pH inhibits bacterial growth; cleanses the lower urinary tract as it flushes from the body
how does sebum impact immunity (chemical factor)
forms protective acidic film over skin surface that inhibits growth of many microorganisms
how does lysozyme impact immunity (chemical factor)
antimicrobial substance in perspiration, tears, saliva, nasal secretions, and tissue fluids
how do interferons (IFNs) impact immunity (2nd line of defense) (antimicrobial substance)
-Small proteins (cytokines) released by activated lymphocytes and macrophages
-Diffuse to adjacent healthy cells, and trigger production of antiviral proteins
-Do not kill viruses, block viral replication
protect uninfected host cells from viral infection
how do the complement system impact immunity (2nd line of defense) (antimicrobial substance)
causes cytolysis of microbes; promotes phagocytosis; contributes to inflammation
how do inron-binding proteins impact immunity (2nd line of defense) (antimicrobial substance)
inhibit growth of certain bacteria by reducing amount of available iron
how do antimicrobial proteins (AMPs) impact immunity (2nd line of defense) (antimicrobial substance)
have broad-spectrum antimicrobial activities and attract dendritic cells nad mast cells
how do natural killer cells impact immunity (2nd line of defense) (antimicrobial substance)
kill infected target cells by releasing granules that contain perforin and granzymes; phagocytes then kill released microbes
how do phagocytes impact immunity (2nd line of defense) (antimicrobial substance)
ingest foreign particulate matter
how does inflammation impact immunity (2nd line of defense) (antimicrobial substance)
confines and destroys microbes; initiates tissue repair
how does fever impact immunity (2nd line of defense) (antimicrobial substance)
intensifies effects of interferons, inhibits growth of some microbes, speeds up body reactions that aid repair
what are antimicrobial aubstances
Enhance innate defense by:
* Attacking microorganisms directly, or
* Hindering microorganisms’ ability to reproduce
-Include:
* Interferons
* Complement system
* Iron-binding proteins
* Antimicrobial proteins (AMPs)
what are the types of interferons and the antiviral mechanism of them
they can be alpha, beta, and gamma
1. virus inters cell and replicates
2. interferon genes swiths on
3. cell produces interferon molecules
4. interferon binging stimulates cell to turn on genes for antiviral proteins
5. antiviral proteins block viral reproduction
describe the complement system
Group of proteins in plasma, work in cascade, circulate in blood in inactive form
-Includes proteins C1–C9, factors B, D, and P, and regulatory proteins
-Provides major mechanism for destroying foreign substances
-Activation enhances inflammation, and also directly destroys bacteria
-Enhances both innate and adaptive defenses
-Activated by three different pathways:
-Classical pathway; Lectin pathway; Alternative pathway
-All three pathways involve conversion of inactive C3 into C3b and C3a
for microbial destruction
review slide 14 complement activation
describe antimicrobial proteins
-Broad spectrum agents; bactericidal
-Can attract APCs (dendritic and mast cells) for immune response
-Ex. thrombocidin, defensins, dermcidin, etc.
describe inro-binding proteins
Suppresses bacterial activities by reducing iron moiety
* Ex. Ferritin, transferrin, lactoferrin etc.
describe natural killer (NK) cells
-Nonphagocytic, large granular lymphocytes that “police” blood and lymph
-Perforin-containing granules: bore hole on target cells
-Kill cancer- and virus-infected cells by releasing granzymes → induce apoptosis
-Attack cells that lack “self” cell-surface receptors
-Secrete potent chemicals that enhance inflammatory response
describe phagocytosis and the two types
-Phagocytes: WBCs that ingest and digest (eat) foreign invaders
Main Phagocytes – neutrophils and macrophages
-Two Types of Macrophages:
* Fixed macrophages – histiocytes, microglia,
Kupffer cells, etc.
* Free (Wandering) macrophages – actively
travel throughout the body
what are the events of phagocytosis
- phagocyte adheres to pathogens or debris (using receptors)
- phagocyte forms pseudopods that eventually engulf the particles forming a phagosome
- lysosome fuses with the phagocytic vesicle forming a phagolysosome
- toxic compounds and lysosomal enzymes destroy pathogens
- sometimes exocytosis of the vesicle removes indigestible and residual material
describe inflammation
-Triggered whenever body tissues are injured due to trauma, heat, irritating chemicals, or infections by microorganisms
MAST CELL
1. increases blood flow
2. activates macrophages
3. increases capillary permeability
4. activates complement
5. stimulates regional clotting reaction
6. increases regional temperature
7. activates adaptive defense
what are the signs and symptoms of inflammation
redness, swelling, heat, pain, immobility
what are the mechanisms of inflammation
1.leukocytosis: neutrophils enter blood from bone marrow
2. margination: neutrophils cling to capillary wall
3. diapedesis: neutrophils flatten and squeeze out of capillaries
4. chemotaxis: neutrophils follow chemical traiil
what are the products of inflammation
-Necrosis – local tissue destruction in area of injury
-Pus – mixture of debris, fluid, dead and dying cells, and necrotic tissue
-Abscess – accumulation of pus in an enclosed space
describe adaptive (specific) immunity
-Ability to defend against specific invading agents
-Activities of T cells and B cells; Exposure to antigen
-Antigens – substances recognized as foreign that provoke immune responses
what are the properties of adaptive immunity
-Specificity – each T or B cell responds only to a specific antigen and ignores all others
-Memory – inactive lymphocytes (memory cells) stay in circulation. Provide immunity against new exposure
-Tolerance – immune system ignores “normal” antigens (self-antigens)
describe exogenous antigen processing (specific immunity)
- phagocytosis or endocytosis of antigen
- digestions of antigen into peptide fragments
- synthesis of MCH-II molecules
- packaging of MHC-II molecules into a vesicle
- vesicles containing anitgen peptide fragments and MHC-II molecules fuse
- antigen peptide fragments bind to MHC-II molecules
- vesciels undergo exocytosis and antigen-MHC-II cpmplexes are inserted into plasma membrane
describe endogenous antigen processing (specific immunity)
- digestion of antigen into peptide fragments
- synthesis of MHC-I molecules
- antigen peptide fragments bind to MHC-I molecules
- packaging of antigen-MHC-I molecules into a vescile
- vesicles undergoes exocytosis and antigen-MHC-I complexes are inserted into plasma membrane
what are the types of adaptive immunity
cell-mediated immunity and anti-body immunity
review slide 23
descibe cell-mediated adaptive immunity
By T-cells, against intracellular antigens
* Bacteria, viruses, fungi inside cells; defective cells (tumor cells)
* Two Population of T cells – based on surface glycoproteins: CD4 cells & CD8 cells
review slide 25 T cell education
review sldie 26 clonal selection
