Unit 6 Adaptive immunity to Bacteria, virus, parasite Flashcards Preview

immunology 1139 > Unit 6 Adaptive immunity to Bacteria, virus, parasite > Flashcards

Flashcards in Unit 6 Adaptive immunity to Bacteria, virus, parasite Deck (57):
1

what are T dependent anitgens

antigens that must be recognized by Th cells in order for immune system to be activated

2

activation of mature B cells by T dependent antigen steps

1. internalization of antigen by APC
2. Processing of antigens by APCs
3. Presenting of antigens to Th cells by APC
4. activation Th to produce cytokines
5. activation of antigen specific B cells with Th cytokines

3

what does humoral immune response to antigens depend on

cooperation of Th, APC such as B cells

4

name the 3 APC

langerhans' cells (dendritic), macrophages and B cells

5

APC express what on their cell surface

class II MHC

6

internalization of antigens occur via

phagocytosis or endocytosis

7

eg of internalization by APC

antigen specific IgM/IgD receptor-mediated endocytosis for B cells

8

what is antigen processing

the Ag is degraded into small fragments of antigenic peptides

9

location of dendritic cells

lymphoid tissue, connective tissue and epithelia

10

location of macrophages

lymphoid tissue, connective tissue and body cavity

11

location of B cells

lymphoid tissue, peripheral blood

12

macrophages present Ag to

Th1 cells

13

b cells present Ag to

Th2 cells

14

where does antigen processing and presentation occur

secondary lymphoid organs (bloodborne pathogens) and lymph nodes (pathogen invading tissue)

15

activation of resting Th lymphocytes require (2)

1. antigen recognition
2. cytokine stimulation

16

what is antigen recognition for Th cells

Th cells through cell surface antigen receptors (TCR) recognize antigen peptide on MHC class II of APC

17

fn of cytokine stimulation for Th cells

resting Th cells activated by cytokines produced by APC

18

eg of cytokine stimulation

IL-1

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fn of lymphokines

promote activation and replication of themselves or B cells

20

what produces lymphokines

activation of specific T h cells

21

activation of B cells require (2)

1. antigen recognition
2. cytokine stimulation

22

what is antigen recognition for B cells

B lymphocytes through IgM/iGD receptors recognize and internalize antigens that will be presented to Th2

23

cytokine stimulation of B cells

locally acting cytokines (IL-4 from Th2) act early in activating Ag-specific B cell (clonal selection)

24

differentiation of activated B cells

clone of activated Ag-specific B cells will proliferate (clonal selection and expansion) and develop into plasma or memory B cells

25

plasma cells aka

antibody secreting or antibody forming cells

26

what is clonal expansion

clone of B cells specific for the Ag will multiply to great numbers

27

clonal expansion produces

mostly plasma cells and small number of memory B cells

28

features of plasma cells

produced in greater number, surface Ig absent, short lifespan, actively secrete Ab

29

features of memory b cells

small numbers, surface IgG/IgA present, long life span years long term immunity

30

thymic independent antigens are

capable of activating without Th cells

31

two types of TI antigens

TI-1 and TI-2

32

TI-1 antigens can

activate multiple clones of immature and mature B cells leading to polyclonal activation (non specific antibody response)

33

eg of TI-1 antigen

bacterial lipopolysaccharide

34

what are B cell mitogens

TI-1 antigens that induce B cell to undergo mitosis

35

what are TI-2 anitgens

large polymeric molecules with highly repetitive structures (eg epitotes)

36

eg of TI-2 antigens

bacterial capsular polysaccharides

37

TI-2 antigens can

crosslink B cell antigen receptor (surface Ig) on mature B cells leading to activation

38

why is immune response not effective against TI-1 antigens

antibodies produced are non specific

39

superantigens are

protein antigens that stimulate Th cells without being processed into peptides by APC

40

how do superantigens work

intact antigen bind directly to TCR and MHC II molecules enabling them to stimulate large number of T cells (2-20% of all T cells)

41

results of superantigen

massive production of cytokines produced by Th causing systemic toxicity and immunosuppression

42

eg of superantigen

staphylococcoal toxic shock syndrome toxin-1 TSST-1

43

effects of TSST-1

excessive amounts of cytokines-> systemic inflammation, hypotension and shock

44

thymocytes that mature in thymus differentiate into

cytotoxic T lymphocytes

45

what are CTL/Tc

CD8 +ive capable of killing abnormal cells (tumor or infected with intracellular pathogens virus)

46

CTL/Tc / killer T cells responsible for

cell mediated immunity

47

development of cytotoxic T cell response

abnormal cell expresses antigenic peptide in class I MHC on cell surface

48

what are the immunological synapse (interface) btwn Tc to abnormal cell

CD8 to MHC I
TCR to antigen

49

describe killing of abnormal cells by CTL

Tc bearing Ag-specific TCR activated and proliferate because of cytokines like Il-2. Tc seek out abnormal cells and destroy them by releasing granules

50

what do granules of Tc contain

perforins like granzymes

51

what are perforins

pore forming proteins related structurally and fnally to complement C9

52

how does perforin work

Tc insert perforins into membrane of abnormal cell --> lysis and death

53

what and where are granzymes found

group of enzymes found in granules of Tc, NK and lymphokine activated cells (LAK)

54

how do granzymes work

enter through holes created by perforins, degrade foreign proteins, trigger apoptosis and DNA degradation

55

fn of cell mediate immune response (Tc mediated response)

destruction of cells infected with intracellular microbes, defense against fungi, protozoa and parasitic worms, graft/acute rejection, destruction of tumor cells

56

what is TIL therapy

tumor infiltrating lymphocyte therapy for cancer

57

lymphocyte activated killer is

Tc and NK cells taken from patient's peripheral blood