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intro to immunology and toxicology > immunology > Flashcards

immunology Flashcards

1
Q

discuss the role and types of toxins

A

microbes often have toxins which cause cell death of host by lysis. inhibit synthesis, activate enzymes, change hormones levels
the host then secretes products which damage neighbouring cells

endotoxins; inside bacterial cell wall. bind to hsot receptors and case an internal response
exotoxins;toxins secreted by pathogen

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2
Q

state three ways apthogens cause damage to host

A

cause cell lysis by secreting toxins
physical blockage; heartworm in dogs
kill hsot directly

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3
Q

how long does it take viruses and bacteria to replicate

A

viruses; under an hour

bacteria; hours-weeks

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4
Q

discuss ways a pathogen can enters the body

A

inhalation; influenza
ingestion; salmonella
sexual acts; gonorrhea
skin breakage; mosquito bites cause itching.

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5
Q

what are symptoms of an invasion

A 
coughing
fever
loss of apetite
swelling
fatigue
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6
Q

why is mammal pregnancy a challenge

A

the featus is 50% ‘‘non self’’ which opens it up to possible immune system attack

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7
Q

what are the 5 stages involved in responding to an infection

A 
realising the pathogon is present
innate response
aquired response
pathogen elimination
immunity
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8
Q

how does a host become aware of an infection

A

it has macrophages positioned at strategic places in the body which are capable of detecting exotoxin production

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9
Q

discuss the physcial and chemical defences in place to prevent most pathogens entering the body and causign pathogenesis

A

physical;
thick layer of skin with tough fiberous keratin proteins
mucus membranes in respiratory tract along with cilia

chemical;
stomach contains hydrochloric acid
dilute acid in urinary tract
lysozymes in tears and sweat; an enzyme which kills bacteria
the fatty acids in skin have antibacteiral qualities

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10
Q

discuss the inflammatory response as part of the innate immune response

A

1) macrophages are activated and perform phagocytosis, release molecules
3) mast cells and platelets are activated which release histamine which causes increases permeability of blood vessels and vasodialation which causes more white blood cells to come to the scene
4) natural killer cells are activated
5) clotting system
6) complement system

overproduction of cytokines occurs which causes release of cytokines into the systemic circulation system; other organs respond. fever, fatigue, anorexia,

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11
Q

discuss how macrophages perform phagocytosis

A

they extend projections around the microbe and engulf it in a vesicle. the vesicle then fuses with a lysosomal vesicle which causes the pathogen to be degraded (its protein is broken into smaller peptides via proteolytic enzymes)

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12
Q

what is an opsonin

A

a protein needed for a macrophage to engulf a pathogen. it forms a bridge between the macrophage and the pathogen

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13
Q

discuss the role of macrophages during the inflammatory innate response

A

phagocytosis

release cytokines

release platelet activation factor which activates platelets which begin producing histamine; this causes vasodialation and increases permeability to WbC’s and protein

release prostaglandins

cause activation, differentiation and proliferation of T and B cells

activate mast cells

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14
Q

discuss the role of natural killer cells

A

these are activated by cytokinins
kill Tumour cells and pathogen infected cells (cytotoxic) by producing proteases, releasing perforins into the cell wall which causes pores to open in the wlal and the cell to burst

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15
Q

discuss the different types of cytokinins

A

interleukin; activation and proliferation of T, B and NK cells

interferon; inhibit viral infections by activating macrophages and neutrophils. a virus enters a cell and the cells releases interfearon to cause neighbouring cells to begin expressing anti viral enzymes

tumour necrosis factor (TNF); inhibits viral replciation

chemokine; controls movement of cells between tissues

colony stimulating factor; causes bone marrow to differentiate and proliferate into different cells.

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16
Q

describe the acute phase response

A

this is a mechanism which involves cytokines being released into systemic circulation which reach the liver and cause it release positive acute phase proteins which inhibit microbial growth. negative acute phase proteing are those whos concentrations decrese in response to inflamation so that the amino acids can be conserved for positive phase protein synthesis

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17
Q

discuss the aquired immune response to pathogen invasion

A

humoural response
B cells release antibodies which bind to extracellular pathogens. complement protein then binds to antibodies and causes the cell to burst open

cell mediated response
macrophages perform phagocytosis of infected cells and present antigens (APC’s).

T helper cells bind to the APC’s and release cytokines to activate B cells and cytotoxic T cells which kill infected cells

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18
Q

how to Tc cells kill infected cells

A

activate nucleases in the cell

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19
Q

describe how long the aquired immune response takes

A

days-weeks.
primary aquired response; lag, log, plateau, decline
secodnary aquired response; decline, log, decline.

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20
Q

how does exposure result in immunological memory

A

memory B cells are produced

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21
Q

discuss the difference between active and passive immunity

A

active; host produces response and generates it own antibodies or Tc cells
passive; host doesnt generate its own resposne; is given antibodies or Tc cells

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22
Q

where do T and B cells mature

A

thymus (gland between lungs)

bone marrow

23
Q

describe the structure of an antibody

A 
Y shaped
glycoprotein
4 chians (2 heavy and 2 light)
hinge region
constant region
24
Q

what is the function of an antibody

A

act as an opsonin between a pathogen and a phagocyte.

25
Q

where does an antibody bind to on a pathogen and a phagocyte

A

the antibody binds to the antigen epitope of a pathogen

the Fc region of the antibody binds to the Fc receptor of a phagocyte which initiates pahgocytosis

26
Q

how many B lymphocytes exist

A

100 million

27
Q

discuss the 5 classes of antibodies

A

IgM;
first antibody made
forms a pentamer
has class switch ability; G, A, E

IgA;
protects mucosal surfaces
is secreted in milk and therefore gives infacts their initial passive immunity
can form dimers

IgG
highest concentration in body
good opsinisation
only antibody which can travel across the placenta
can neutralise toxins by binding to their active site

IgD
is bound to B cell surface and signals that the B cell is mature

IgE
involved in allergies
involved in immune response against parasites
is on mast cells; when the antibody binds to a pathogen the mast cell releases histamine

28
Q

what do blood groups mean

A

it is the antigen molecule on your RBC’s.
A type has A antigens and anti B antibodies
B is the opposite of A
AB has A and B antigens and no antibodies
O has no antigens but both antibodies. can give blood to anyone but can only recieve blood from another O

29
Q

whats another important thing to consider when doing a blood transfusion

A

the rhesus factor of the giver/recipient

over 30 Rhesus antigens exist

30
Q

how do pathogens evade the immune response

A

occupy intracellular sites; inside of cells that cant be attacked by the immune system

cover themselves in the hosts macromolecules or mimic hsot macromolecules

alter gene expression so that antigens presented change constantlys

suppress the host immune system; stop production of immune cells or secrete enzymes which stop an immune response

evolve in a way so that host molecules cause growth rather than death

31
Q

how do intracellular pathogens avoid phagocytosis

A

stop the phagosome and lysosome from fusing
escape form the phagosome
resist death in the pagosome

32
Q

how do extracellular pathogens avoid the immune response

A

secrete proteases to degrade the antibody or alter the antibody so that opsonisation cant happen

produce surface molecules which bind to the antibody and mean the antibody cant bind to the phagocyte. protein A and protein G

secrete toxins which kill the phagocyte or make it unable to move

have surface structures which stop phagocytosis happening; pilli, capsule

33
Q

discuss 3 examples of antigenic variaiton

A

microbe has genomic rearrangement which causes a sudden shift in antigens presented

microbes have DNA replicating enzymes prone to error so that the antigen composition changes gradually

as a microbe matures it changes its composition of antigens so its one step ahead of the immune system

34
Q

whats requried for antigenic variation

A

multiple antigens
switching ability
multiple antigen sequences

35
Q

discuss the case of T. brucei

A

a protozoa with over 1000 antigens

99% of population die then 1% switch antigens and begin thriving and evading humeral response

pathogen is transmitted by Tseste fly and causes african sleeping sickness;25,000 deaths a year

treatment involves anti parasitic drugs

36
Q

define specificity in relation to immunological test principles

A

an antibody will only combine with a single antigen

37
Q

discuss cross-reactivity in relation to immunological test principles

A

some antibodies have the ability to bind with more than one antigen

38
Q

describe the agglutination test and discuss its pros/negs

A

measures amount of Ab/Ag present
a latex bead with Ab’s attached is added to serum. if antigens are present they will clump up on bead and agglutinate
simple and quick but has little sensitivity

39
Q

what is titer in relation to immunological tests

A

the reciprocal value of the most dilute solution leading to a positive immunological test result. worked out so that immunological tests are quantifiable

40
Q

describe the complement fixation test

A

measures quantities of Ab present
serum is mixed with known quantities of Ag and complement protein. the amount of unbound antigen/ complement indicates amount of antibody present

41
Q

describe the precipitation test

A

measures presence of Ab/Ag
visible observation of precipitated Ag-Ab signals quantities of molecules present
not very sensitive; large amount of AB/Ag must be present for a positive result

42
Q

describe the ELISA test

A

a test whcih can be used to detect Ab, Ag, toxins, hormones etc
the ELISA plate has an antibody bound to an emzyme in a way that the presence of an antigen causes a substrate to be converted to a product which causes a colour change reaction to occur which can be measured used spectrophotometry

43
Q

discuss the types of ELISA test that exist

A

direct ELISA
indirect; secondary antibody
sandwich; third antibody
competitive; inhibitor antibody leading to no colour change reaction

44
Q

discuss limitations of ELISA

A

positive result may just mean patient has been infected in the pst

false negative results are possible if the body is a bad producer of the antibody or if competing substances for antibody exist

false positive results are possible due to cross reactivity

45
Q

what is western blotting used for

A

detection and quantification of a protein

used to confirm the results of an ELISA test

46
Q

define self reactive lymphocyte

A

a one which attacks the bodies own cells

47
Q

why do the 2 explanations of why disease occur?

more specifically, what are 3 explanations of why autoantibodies are produced>

A

usually an environmental event activates self reactive self-lymphocytes.a microbial invasion occurs which activates B and T cells complimentory to the microbes antigen. the microbes are also reactive against the bodies own ‘‘self antigen’’

rarely its genetic

1) cross reactive epitopes; a pathogen has a similar epitope on its antigen to a self antigen so B cells recognise self material
2) severe host tissue damage such as burns cause self antigens to be released which are taken up by dendritic cells and which causes autoreactive Th cells to be activated
3) mitogens stimulate B cells to produce antibodies for self antigens

48
Q

discuss 3 examples of autoimmune diseases

A

type 1 diabetes; B cells attack islets of langerhans so the body can no longer produce insulin

multiple sclerosis; body attacks CNS

haemolytic anaemia; antibodies attacking RBC’s

49
Q

what is myasthenia gravis

A

autoimmune disease
autoantibodies are produced which bind to the acetylcholine receptor and block it. electrical signals cant be passed on so muscle contraction cant occur.
the autoantibodies also degrade the receptor

50
Q

what is graves disease

A

an autoimmune disease in which autoantibodies bind to throid tissue and cause excessive expression of thyroid hormones

51
Q

what is hashimotos thyroiditis

A

T cells and B cells invade the thyoid and casue destruction leading to loss of hormone production

52
Q

what is pernicious aneamia

A

when autoantibodies are prodcued which bind to floating intrinsic factors in the stomach and blocks B12 from binding to them so vitamin b12 cant be absorped

53
Q

discuss function of dendritic cells

A

cells that drink body fluids and then present antigens on their surface for Th cells

54
Q

what % of industrialised countries are effected by autoimmune diseases

A

5%

intro to immunology and toxicology (3 decks)

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