Notiuni Generale de Imunologie

7/29/2019 Notiuni Generale de Imunologie

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Curs Introductiv

Istoric, Teorii selective si instructive,

Sistem imun specific si nespecific,

Echilibrul dintre fiziologic si patologic


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The Immune SystemDefends body against pathogens

Can distinguish between self and non-self

General Defence System (innate)Non-specific = acts against all pathogensRapid

1. First line of general defenceSkin = barrier. Sweat (acidic pH)Clotting = also helps protect skinLysozyme = enzyme in saliva, sweat, tears. Attacks bacterial cell walls

Mucous (respiratory, digestive, urinary & reproductive tracts) = traps pathogensCilia = little hairs that help clear mucous (and pathogens) from respiratory tractAlimentary canal = lysozyme in saliva, stomach HCl kills many pathogens, specialisedimmune areas in the GI tract, very high turnover of epithelial cells, antibodies

Specific Defence System (adaptive)


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2. Second line of general defencePhagocytic white blood cells (leukocytes) = destroy pathogens that enterComplementInflammation

Phagocytes (Phago= eat; cyte=cell)attracted to a site of infection (chemotaxis) by chemicals released by injured cellsThree types neutrophils (short lived),

monocytes (short-lived..in blood) and macrophages (long-lived..in tissue)


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Variola afectiune eradicata ca urmare

a unei campanii de vaccinare


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Vaccinare

14 mai 1796

Edward Jenner ilimunizeaza pe JamesPhips, in varsta de 8 ani,cu materialul biologicextras din pustula uneimulgatoare, SarahNelmes, afectata decowpox (vaccina). Pestecateva saptamani, baiatul

este imunizat cu materialbiologic extras de la unpacient cu variola, dar nudezvolta boala.


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Figure 1-15


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Macrophages very large white cells that can movearound body, or remain in certain tissues. Long lived,

act as scavengers

Immune organs


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Complement set of 30 proteins found in plasma that are activated by

infection

complicated chain reaction that leads to the bursting ofviruses and bacteria

made in the liver

Interferons set of proteins produced by virally infected cells cells to limit the spread of viral

infections, by inducing a state of resistance in healthy cells. induced by viruses, bacteria and other signals from the immune system

Inflammation infected cells (mast cells) release histamine, which is a vasodilator. This causeslocalised swelling, redness, heat, pain. Can also cause high temperature.

brings white cells to the area of infection Anti-histamines

2. Second line of general defence cont.


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Specific Defence System (Adaptive Immune System)

Antigens foreign molecules that

generate antibody production

Antibodies (immunoglogulins) proteinsproduced by lymphocytes in responseto antigens

Monocytes develop into macrophages which phagocytose foreign particles (antigens)Lymphocytes -


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B lymphocytes mature in Bone marrow lymphatic tissue, especially spleen and lymph nodes

Tlymphocytes mature in the Thymus

Lymphocytes

Large nucleus


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B lymphocytes make antibodies = immunoglobulins

1000s of different B cells, each recognises adifferent antigen on the surface of a macrophage.Each antigen stimulates production of a singlespecific antibody

B cells (along with T cells) come in contact with antigen.They are stimulated (by T cells) to produce many clones,plasma cells, which make antibodies.

B-lymphocytes

AntibodiesCan bind to pathogens and preventthem from infecting cells. Pathogensare then destroyed by phagocytes

Can inactivate pathogens by causingthem to clump together

Can trigger the complement system,resulting in pathogens being burst

Memory B cells faster, more sensitive reaction= secondary response

H B ll k


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MacrophagePhagocytoses pathogenand displays antigens onsurface

B-cellsEach recognisea differentantigen. Thecorrect onedevelops into

Plasma cellsClones of thecorrect B-cell,which produceantibodies

1st meeting a pathogen, thisprocess takes 10-14 days

Memory B cell= subesquentmeetings, takes about 5 days

How B-cells work

Pathogen (e.g. bacteria, virus)

Macrophage


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T-lymphocytes

Helper T-CellsRecognise antigens onsurface of leukocytes,especially macrophagesEnlagre and form aclone of T-helper cellsSecrete interferon andcytokines whichstimulate B-cells andstimulate killer -cellsCan be infected by HIV

Killer T-CellDestroy abnormal bodycells, e.g. virus infectedor cancer cellsStimulated by cytokines(THcells)

Release perforin, whichforms pores in targetcells. This allows waterand ions in = lysis

Suppressor T-CellsControl theimmune systemwhen the antigen/pathogen hasbeen destroyed

Only recentlydiscovered solittle is knownabout them

Memory T-CellsCan survive a long timand give lifelongimmunity frominfectionCan stimulate memory

B-cells to produceantibodiesCan trigger productionof killer T cells

Mature in Thymus, which is most active just before and after birth.The thymus starts to shrink during puberty.

Killer T cell H T ll k


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Abnormal cell e.gcancer cell, infected cell

Normal cell

Antigen

Killer T-cellrecognises antigen

Clones of killer T-cellattach to antigen

Helper T-cell stimulatescorrect killer T-cell to

multiply

Killer T-cells releaseperforin pores

Abnormal cell gains

water, swells andbursts

Helper T-cell alsostimulates B-cellsto make antibodies

Memory T-cells stay incirculation

Suppressor T-cellsturn off immune

response

XX

X

How T-cells work


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Duration of immunityMemory B-cells circulate for a long time. If the same pathogen infects thebody again, these B-cells can produce large amounts of specific antibodyvery quickly. This is why you usually dont suffer from the same infectiontwice.Memory T-cells survive a long time and trigger an immune response

Tumours in most cases the body recognises tumours as being bad, because theyexpress abnormal molecules on the cell surface. However sometimes the body doesntnotice and cancers can develop

Immune disordersSometimes the body produces antibodies against its own tissues e.g. autoimmunediseasese.g. rhumatoid arthritis, Crohns disease, SCID (bubble boy disease),asthma

Allergies occur when the body reacts to materials which should notbe antigenic e.g. peanuts
http://images.google.ie/imgres?imgurl=http://www.texomapeanut.com/inn/Inshell%2520peanut.jpg&imgrefurl=http://knighthoodofbuh.org/board/phpBB/viewtopic.php%3Ftopic%3D2580%26forum%3D22%262&h=408&w=440&sz=40&tbnid=2Vf8cNAjxW4J:&tbnh=114&tbnw=123&start=1&prev=/images%3Fq%3Dpeanut%26hl%3Den%26lr%3D%26sa%3DGhttp://images.google.ie/imgres?imgurl=http://edcenter.med.cornell.edu/CUMC_PathNotes/Skeletal/757.GIF&imgrefurl=http://edcenter.med.cornell.edu/CUMC_PathNotes/Skeletal/JOINTLIST.html&h=316&w=465&sz=84&tbnid=Guf8EZ7WIHkJ:&tbnh=84&tbnw=124&start=1&prev=/images%3Fq%3Darthritis%26hl%3Den%26lr%3D


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Induced Immunity

Active immunityProduction of a persons own

antibodies. Long lasting

Passive immunityAn individual is given antibodies by another

Short-term resistance (weeks- 6months)

Natural ActiveWhen pathogen

enters body in thenormal way, wemake antibodies

Natural PassiveBaby in utero

(placenta)Breast-fed babies

Artificial PassiveGamma globulin

injectionExtremely fast, but

short lived (e.g. snakevenom)

Edward Jenner

Artificial ActiveVaccination usually

contains a safe antigenfrom the pathogen.

Person makesantibodies without

becoming ill
http://images.google.ie/imgres?imgurl=http://tubes.ominix.com/art/animals/insects/rattle-snake-04.png&imgrefurl=http://tubes.ominix.com/art/animals/insects/&h=414&w=300&sz=105&tbnid=JusTXmSlo2cJ:&tbnh=120&tbnw=87&start=1&prev=/images%3Fq%3Dsnake%26hl%3Den%26lr%3D%26sa%3DG


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Macrofag


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Figure 1-23


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Patogenii carepenetreaza prinbarierele antomice sifiziologice suntintampinati desistemul imunnespecific. Ulterior,va intra in functiune,eventual, sistemulimun specific.Interactiunea dintre

cele doua sisteme serealizeaza prinmolecule desuprafata si citokine.


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Trei faze aleapararii gazdei.Fiecare dintre eleimplica o strategiedistincta. 1)bariere pre-existente; 2)sistemul imun

innascut incepe salupte in mod activ;3) intra in actiunesistemul imunspecific. La uncontact ulterior cuantigenul,limfocitele cu

memorie vor facilitaun raspuns mairapid si maieficient.


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Organe limfoide

primare: timusul si

maduva osoasa

Organe limfoidesecundare: splina,

ganglioni limfatici,

MALT (tesut limfoid

asociat mucoaselor)


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Boala poate apare in situatia cand sistemul imun declanseaza un raspuns imun

necorespunzator.


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Figure 1-32

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Notiuni Generale de Imunologie

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