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Microbiology Exam 1 > Section IV: Adaptive Immunity > Flashcards

Section IV: Adaptive Immunity Flashcards

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0
Q

What is specificity

A
  • recognition of foreign substances

- a small molecule called hapten can also act as an antigen, but only when bound to a larger molecule

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1
Q

What are the characteristics of adaptive immunity

A
  • specificity
  • self recognition
  • memory
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2
Q

What is memory

A

following the first exposure to antigen, immune system develops memory to provide rapid secondary response to same antigen

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3
Q

What is the bodies two part strategy for eliminating foreign material

A
  • humoral response

- cell mediated response

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4
Q

What is a humoral response

A

eliminates antigens that are extracellular, for example bacteria in the bloodstream

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5
Q

What is a cell mediated response

A

deals with antigens residing within a host cell, for example a virus infected cell

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6
Q

What is the structure of an antigen

A

large carrier molecule with epitopes projecting from surface. Epitopes interact with antibody and T cells

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7
Q

What are the origins of exogenous antigens

A

those that have entered the body from the outside, for example by inhalation, ingestion, or injection

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8
Q

What are the origins of endogenous antigens

A

those that have been generated within the cell, as a result of normal cell metabolism, or because of viral or intracellular bacterial infection

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9
Q

What are superantigens

A
  • do not behave as normal antigens. Rather than attaching to the MHC groove and triggering a normal immune response, superantigens attach onto the sides of the binding site
  • as a result, T cells go on an unregulated rampage, uncontrollably releasing regulatory molecules-such as interferons- in toxic amounts
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10
Q

What are Class I MHC’s

A
  • presents proteins (antigens) from inside cell
  • also presents abnormal proteins on surface of virus infected cells or tumor cells for inspection by cytotoxic T cells
  • cytotoxic T cells will destroy “non-self” proteins
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11
Q

What are Class II MHC

A

presents antigens from outside cell

-MHC II proteins display non-self which will be recognized by helper T cells

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12
Q

Where are MHC II proteins found

A

ONLY on immune cells called antigen presenting cells

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13
Q

What are activated dendritic cells

A

Found in those tissues which are in contact with the environment: in the skin and lining of nose, lungs, stomach, and intestines

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14
Q

What are activated macrophages

A
  • present antigen early in infection
  • the presence of the antigen activates macrophages
  • activated macrophage processes the antigenic material
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15
Q

What happens following processing by an activated macrophage

A
  • epitopes from the antigen are presented on the macrophage surface in combination with MHC proteins
  • presented antigen is the recognized by helper T cells
  • recognition activates the helper T cells
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16
Q

What do activated helper T cells regulate

A

Cell mediated and Humoral immunity

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17
Q

Does a T cell produce antibodies

A

no… never… never ever

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18
Q

Do T cells interact with free antigens

A

no.

- anitgen must be presented to T cell by another cell (CD4 cell)

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19
Q

Where are inactive (naive) T cells located

A
  • restricted to circulation

- cannot migrate into tissues

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20
Q

What is required for activation of T cells

A
  • must encounter antigen presented on cell in antigen-MHC complex
  • must also be concurrently stimulated by other molecules
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21
Q

What does activation of T cells lead to

A
  • formation of specific effector cells types

- effector T cells have different roles in cell mediated immunity

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22
Q

What are functions of activated T cells

A
  • proliferative, develop into different effector cells
  • bring antigens to naive T cells
  • Release lymphokines which act as messengers, they do not respond to specific antigen, instead lymphokines act to recruit other cell types, particularly macrophages
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23
Q

What are CD4 T lymphocytes and what is there roll

A
  • T cells that carry the CD4 marker can be T helper cells

- The role of T helper cells is to judge the significance of antigen presented by APC’s

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24
Q

What happens following recognition by T helper cells

A

B cells development stimulated and other T cells by releasing cytokines
–impacts both cell mediated and humoral immunity

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25
Q

What are Th1 cells

A
  • judge antigen presented by macrophages. If a Th1 cell recognizes the antigen it responds by activating the macrophage
  • Th1 cells orchestrate the cell mediated response by releasing lymphokines to stimulate proliferation of T cells, stimulate natural killer cells and recruit macrophages
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26
Q

What are Th2 cells

A
  • judge antigen presented by B cells
  • if Th2 cell recognizes the antigen it responds by activating the B cell to produce antibody
  • Th2 cells also stimulate proliferation of B cells
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27
Q

What are T regulatory cells

A

also carry CD4 marker

-block induction and activity of T helper cells and B cells

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28
Q

What are CD8 T lymphocytes

A

Most T cells have the CD8 marker

  • T cytotoxic cells induce apoptosis in self cells infected with virus or other microbe. Can also destroy cancerous cells
  • > T cytotoxic cells recognize dysfunctional self cells by recognition of antigen presented on MHC I molecules
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29
Q

What are T memory cells

A

long lived anitgen activated T cells that respond with heightened reactivity to secondary exposure with specific antigen

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30
Q

How is Type IV hypersensitivity immune response mediated and how does it occur

A

mediated by cellular immunity

-occurs when effector T cells regulate delayed allergic reactions

31
Q

What happens when CD4 and CD8 are out of balance

A

compromised cellular immunity

32
Q

What do lymphokines activate

A

activation of macrophages

  • activation of polymorphonuclear leukocytes
  • activation of lymphocytes
  • other lymphokines
33
Q

What is macrophage activation factor (MAF)

A

activates macrophages and allows them to act as cytotoxic cells that non-specifically kill tumor cells

34
Q

What is Macrophage migration inhibitory factor (MIF)

A
  • Inhibits random migration of macrophages, role in T cell activation
  • MIF is now recognized as a principle cytokine modulating T cell/macrophage interactions in the expression of delayed hypersensitivity and acquired cellular immunity
35
Q

What are chemotactic factors

A

substances possessing chemotactic activity

36
Q

What is leukocyte inhibitory factor

A

inhibits the random and directed migration of polymorphonuclear leukocytes

37
Q

What is eosinophil stimulation factor

A

stimulates eosinophil migration and is produced by mitogen or specific Ag stimulation of spleen cells fro mice infected with Schistosoma mansoni

38
Q

What are interleukins

A

structurally and functionally distinct soluble proteins secreted by different types of leukocytes that are involved in cell to cell communication

39
Q

What are cytotoxic factors

A

term for a factor or an agent that has a specific destructive effect on cells

40
Q

What is growth inhibitory factor

A

found in normal human brain tissue and is expressed exclusively in the nervous system. GIF inhibits survival and the outgrowth of neurites in cortical neurons.
-Drastically reduced concentrations of this factors are found in the brains of patients with Alzheimer’s disease

41
Q

What is osteoblastic factor

A

stimulates the formation of osteoblast cells in bone

42
Q

What is collagen production

A

factors stimulating formation of collagen

43
Q

What are interferons

A

proteins that elicit a virus non-specific antiviral activity. Also posses anti-proliferative and immunomodulating activities and influence the metabolism, growth and differentiation of cells in many different ways

44
Q

What is Transforming growth factor

A
  • TGFs were identified initially as proteins secreted by virus-transformed mouse cells
  • TGF-beta is the most potent known growth inhibitor for normal and transformed epithelial cells, endothelial cells, fibroblasts, neuronal cells, lymphoid cells and other hematopoietic cell types
45
Q

What does TGF-beta inhibit

A

proliferation of T lymphocytes

-shuts down clonal expansion

46
Q

What mediates Humoral immunity

A

B lymphocytes

47
Q

What do B-cells do in response to antigens

A

proliferate and then differentiate into plasma cells which function to produce antibodies

48
Q

What are the characteristics of antibodies

A
  • produced by plasma cells
  • antibodies are found in blood serum
  • antibodies also found on the surface of B lymphocytes
49
Q

Why are there antibodies found on B cells

A

allows B cell to interact with specific antigens

  • antigen interaction causes the B cell to differentiate into plasma cells and into memory cells important concept
  • allows plasma cells to to produce free antibody
50
Q

What is the role of antibodies

A
  • agglutination

- precipitation

51
Q

What recognizes antigen/antibody complexes

A

phagocytic cells

52
Q

What is an antitoxin

A

antibody with the ability to neutralize a specific toxin

53
Q

What is an opsonin

A

any molecule that acts as a binding enhancer for the process of phagocytosis
-antibodies can be opsonins
opsonin~helper

54
Q

What is the basic structure of an antibody

A

consist of two high molecular weight polypeptide chains called heavy chains and two lower molecular weight polypeptide chains called light chains

55
Q

What type of bond holds the chains together

A

disulfide bonds

56
Q

What is the Fab- fragment

A

binding portion, binds the antigen

57
Q

What is the Fc- fragment

A

crystalline fragment, determines the antibody class

58
Q

Where is the variable region found on the antibody

A

at the end of the Fab region

59
Q

What is the constant region

A

encompasses the entire Fc region as well as one domain of both heavy and light chains in the Fab region

60
Q

What is IgG

A
  • monomer
  • most abundant immunoglobulin
  • agglutinates and precipitates antigen, also can act as antitoxin
  • When multiple bind to surface of antigen a specific complement protein binds to FC region to begin complement cascade
  • crosses placental barrier to provide passive immunity to fetus
61
Q

What is IgM

A
  • pentamer
  • Largest immunoglobulin, large size prevents from entering tissue
  • first class to be produced in response to antigen
  • most efficient class at activating complement cascade
62
Q

What is IgA

A
  • pentamer
  • found in body secretions
  • exists as monomer in blood, but secreted as dimer
63
Q

What is IgE

A
  • monomer
  • barely detectable in normal blood, most bound via Fc region to mast cells ad basophils
  • involved in allergy, triggers release of histamines by binding mast cell
  • can cause anaphylactic shock
64
Q

What is IgD

A
  • Monomer
  • found in low levels in serum, role is uncertain
  • primarily found on B cells surfaces where it function as a receptor for antigen
  • does not bind complement
65
Q

What is the complement system

A

series of proteins that constantly circulate in blood and tissue fluid
-augment, or complement the activities of antibodies

66
Q

What are the characteristics of complements

A
  • complement proteins are always circulating and can be quickly activated
  • when activated various complement proteins attach to cell surfaces-forms membrane attack complex
  • complement binding prepares cell for phagocytosis
  • complement binding can release active substances
  • complement binding can lyse cell
67
Q

What is the classical complement cascade

A

antibody binding to antigen is necessary for cascade

  • C1 binds to Fc portion of antibody
  • C1 converted to enzyme which splits into C2 and C3
  • C3 splits to C3a and b
  • C3b combines with C4b2b to create C5 convertase
68
Q

What is the alternative complement pathway

A
  • bypasses portion of classical system b/c no antibody/antigen binding is required
  • involves 4 proteins, factors B and D, properdin, and C3
  • activated by:
  • > plant, fungal, bacterial polysaccharides
  • > bacterial lipopolysaccharides
69
Q

What are the functions of complements

A
  • formation of membrane attack complex (MAC) that causes cell lysis, especially true when bacteria is antigen
  • complement proteins mark antigens and attract phagocytic cells
  • complement proteins can act as opsonins
  • complement proteins can act as anaphylatoxins leading to anaphylaxis
70
Q

What can occur if complement is not controlled

A

vascular damage and initiation of coagulation

-following initiation of coagulation, components of coagulation are consumed and destroyed, results in hemorrhage

71
Q

What is the primary immune response

A
  • the first response to a particular antigen
  • the adaptive immune system requires 1 week or more to respond
  • first antibody produced during adaptive immune response is IgM then IgG
72
Q

Whatis an T cell independent antigen

A

do not require presentation, rather B cells respond directly to antigen

73
Q

What is a T cell dependent antigen

A

require presentation to helper T cell

74
Q

What is the secondary immune response

A
  • memory cells are stimulated consequently the adaptive immune response occurs only after a short delay
  • level of IgG is higher and longer lasting
  • less antigen needed to elicit response of immune system
  • memory may persist for years

Microbiology Exam 1 (8 decks)

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