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Microbiology > Adaptive Immunity > Flashcards

Adaptive Immunity Flashcards

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Biology 101 flashcards
1
Q

Adaptive immunity can be classified into 3 categories. list them

A
  • Active immunity: occurs when immunocompetent host is exposed to foreign challenge and the host native cells respond with specific products
  • passive immunity: preformed immune products are administered to host (injections)
  • adoptive immunity: immunocompetent cells are transplanted to an immuno incompetent host to restore immune system
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2
Q

explain how T4 lymphocytes are classified based on whats presented on their surface

A

T4-Lymphocytes are T lymphocytes with CD4 surface molecules. they also have an epitome receptor called T Cell Receptors (TCR).

  • CD4 together with TCR are capable of recognizing peptides on exogenous antigens bound to MHC-II molecules on the surface of antigen-presenting cells like dendritic cells
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3
Q

what is the primary role of T4-lymphocytes

A
  • regulate bodys immune response
  • once T4-lymphocytes are activated by dendritic cells they proliferate and differentiate into T effector lymphocytes that regulate immune response via cytokines
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4
Q

explain how T8 lymphocytes are classified based on whats presented on their surface

A
  • they are T8-lymphocytes wiht CD8 surface molecules.
  • they have T Cell Receptors (TCR) on their surface
  • TCR and CD8 together bind endogenous antigens bound to MHC-I molecules
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5
Q

what is a more appropriate name for Antigen (Ag)?

A

immunogen

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6
Q

what are Adjuvants

A

substances that enhances an immune response by facilitating the uptake of Antigen Presenting Cells (APS)

Or other definition in the slides;

a substance that stimulates a nonspecific immune response to slowly releasing immunogen from depot after injection

(some human vaccines contain adjuvant Aluminum phosphate or Aluminum hydroxide in diphtheria toxoid)

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7
Q

how do Antigens activate immune response?

A
  • they activate macrophage and dendritic APC which leads to activate of T-cell=CMI
  • they activate B cells= AMI (Antibody Mediated immunity)
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8
Q

are all immunogens antigens? what about the reverse?

A

All molecules that have property of immunogenicity also have property of antigenicity.

  • not all antigens are immunogens such as haptens
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9
Q

what are the features that determine immunogenicity?

A
  1. recognition of foreginness
  2. size
  3. chemical structure and complexity
  4. genetic makeup of host
  5. dosage, route and timing of antigen administration
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10
Q

what are Epitopes?

A

immunologically active sites of immunogen that bind to antigen-specific receptors on lymphocytes or to antibodies

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11
Q

what areas do B & T cells bind to on epitopes?

A
  • B cells bind epitopes to highly accessible sites exposed on surface of immunogen
  • T cells bind epitopes on sites where peptides bound to MHC molecules of APC or altered self cells
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12
Q

define HLA Complex and where can they be found

A

Human Leukocyte Antigen Complex

found only in humans

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13
Q

define MHC Complex and where can they be found

A

Major Histocompatibility Complex

found in many vertebrates

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14
Q

what is one of the roles of MHC?

A

involved in recognition of antigens and displaying them to other immune cells in order to produce immune response

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15
Q

Explain the steps in the activation of a clone Cytotoxic T (Tc) Cell

A
  1. Antigen presentation: APC (ex: dendritic cell) presents epitope w/ MHC-II protein to helper T Cells (Th)
  2. Th differentiation: infected APC secrete IL-2 which causes Th to differentiate into type 1 Helper T (Th1) Cells
  3. Clonal Expansion: signaling from APC & IL-2 from Th1 Cell activate Tc cells that recognize MHC-I protein-epitope complex. IL-2 triggers Tc cells to divide forming a clone of active Tc and memory T Cells
  4. Self Stimulation: active Tc cells secrete IL-2, becoming self-stimulatory
  • The adaptive immune response does not initiate at site of infection, it initiates at lymphoid tissue (i.e lymph node) where it interacts w/ lymphocytes.
  • initial event is cell-mediated activation of Tc
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16
Q

explain the process in which exogenous antigens are processed.

A
  1. dendritic cell phagocytizes APC. Lyosome w/ MHC-II molecules in its membrane fuses with phagosome. MHC-II molecules bind w/complementary epitopes
  2. vesicle fuses w/cytoplasmic membrane
  3. MHC-II epitope complex form on cell membrane
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17
Q

Explain the Perforin-Granzyme Cytotoxic Pathway

A

used for cell apoptosis.

  • virus-infected cell binds to an active Cytotoxic T (Tc) cell
  • the perforin-granzyme cytotoxic pathways: Tc cell releases perforin and granzymes which enter infected cell through perforin complex pore and activate enzymes of apoptosis
  • the CD95 cytotoxic pathway: CD95L binds to Tc cell which activates enzymatic portion of the infected cells CD95 such that apoptosis is induced
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18
Q

what is another word for antibodies?

A

immunoglobins

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19
Q

define Polyclonal Antibodies

A

a complex mixture of several antibodies (immunoglobins) that recognize and bind to different epitopes of a single antigen

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20
Q

define monoclonal antibodies

A

single antibody species that will only bind single specific site

21
Q

List the 5 types of immunoglobins

A
  • IgG: immunoglobin Gamma (75% of Ig)
  • IgM: Immunoglobin mu (10-12% Ig)
  • IgA: immunoglobin alpha (15% of Ig)
  • IgE: Immunoglobin epsilon
  • IgD: Immunoglobin delta
22
Q

all antibodies are immunoglobins but not all immunoglobins are antibodies

A

all antibodies are immunoglobins but not all immunoglobins are antibodies

23
Q

what is antiserum

A

serum that contains antibodies

24
Q

IgM

A
  • 1st antibodies to circulate in response to initial exposure to antigen, their concentration in blood declines fast
  • consist of 5 Y-shaped monomers arranged in pentagonal structure (pentamer)
  • too large to cross placenta
25
Q

IgG

A
  • most abundant
  • readily crosses walls of blood vessels and enters tissue fluids
  • IgG crosses placenta and provides passive immunity in fetus
  • Monomer
26
Q

IgA

A
  • produced by cells in mucous membrane
  • prevents attachment of bacteria/viruses to epithelial surfaces
  • found in many body secretions
27
Q

IgD

A
  • dont activate complement system and cant cross placenta
  • mostly found on the surface of B cells and probably functioning as antigen receptors that helps initiate the differentiation of B cells into plasma cells and memory B cells
  • monomer
28
Q

IgE

A
  • only small fraction of antibodies in blood
  • tails attach to mast cells and basophils and when triggered by antigen, they cause cells to release histadine and other chemicals that cause allergic reaction
29
Q

where does the humoral (AMI) response occur?

A

extracellular spaces. Free-antigens

30
Q

Explain the activaiton process of B cells to produce antibodies

A
  1. Recogniton & Attachment: APC receptors recognize and attach to an antigen
  2. Phagocytosis: antigen is phagocytized and digested
  3. Display of antigen: Antigen fragments are displayed on surface of B cell which attracts a matching T cell
  4. cytokine secretion: T helper cell secrete cytokines which activate B cell
  5. Clonal expansion: The activated B Cell beings clonal expansion which produces army of antibody producing plasma cells and memory cells
  6. 7.
31
Q

explain the process of T-dependent immunity: clonal selection

A

most antibody immune responses depend on interaction with T Helper Cells (Th)

  1. Antigen presentation: APC (i.e dendritic cell) presents antigen to complementary T helper cell
  2. Th differentiation: Th Cell differentiates into Type 2 T helper Cell (Th2)
  3. Th2 cell secretes IL-4 which activates B cell
  4. B cell differentiates into antibody-secreting plasma cells
  5. also differentiate into long-lived memory cells
32
Q

describe the 2 types of antibody response.

A
  • primary response: response to initial antigen exposure. antibodies visible in serum w/ days-weeks. amount of antibodies produced usually low. IgM 1st appears followed by IgG which provides longer term immunity
  • Second exposure: 2nd exposure to same antigen stimulates memory cells (formed at time of initial exposure) to rapidly produces large amount of antibodies. antibody levels are high and remain high for longer. antibodies produced usually IgG
33
Q

list the different types of adaptive immunity

A
34
Q

list the different disorders of the immune system

A
  • hypersensitivity
  • autoimmune disease
  • immunodificiency disease
35
Q

define hypersensitivity and their reactions.

A

an exaggerated immune response that harms the host. this occurs when the host is sensitized to previously exposed antigen and body reacts in damaging manner

  • Anaphylactic (Type 1)
  • cytotoxic (Type 2)
  • Immune complex (Type III)
  • Cell-mediated (delayed-type) reactions (Type IV)
36
Q
A
37
Q

define cytotoxic reaction

A

Type II of hypersensitivity

  • activation of complement by combination of IgM and IgG antibodies with antigen cell. causes lysis of target cell
  • results in hemolytic anemia, ABO transfusion reactions, Rh hemolytic disease, drug-induced cytotoxic reactions
38
Q

define immuno complex

A

Type III of hypersensitivity

  • involve antigen: antibody complexes that activate complement
  • normally immuno complex are phagocytized however small immune complex may evade phagocytosis and circulate blood until they become trapped in joints, tissues or organs
    • in these sites they react w/ complement which results in inflammation and cause neutrophils to release enzymes that damage nearby tissue
39
Q

define Delayed Cell-Mediated Reactions

A

Type IV of hypersensitivity

  • interaction of antigen to specifically sensitized T cells result in T cell proliferation and the release of potent inflammatory cytokines (INF-y & IL-2)and activation of macrophages
  • Ex: allergic dermatitis usually caused by haptens that combine w/ proteins in the skin
40
Q

define autoimmunity

A

body development of intolerance of antigens on its own cell. immune response to ones own tissue antigens

results in a disease state characterized by AMI or CMI against bodys own tissues (auto antigens)

41
Q

define immunodeficiency

A

absence of a sufficient immune response

42
Q

list the types of immunodeficiency

A
  • Congenital (primary immunodeficiency disease)
  • acquired (secondary immunodificiency disease)
43
Q

define Chronic granulomatous disease

A

a type of congenital immunodeficiency

  • inherited, affects 2nd line of defense. inability to produce reactive forms of oxygen which is required to destroy phagocitized bacteria
44
Q

define Severe Combined Immunodeficiency Disease (SCID)

A

a type of congenital immunodeficiency disease

  • defect in 3rd line of defense. failure to develop lymphoid stem cells which means they cant produce B or T cells and results in failure to launch immune response.
45
Q

define DiGeorge syndrome

A

T cell deficiencies

  • failure of Thymus to develop.
  • individuals usually die of viral infections while remaining resistant to most bacteria
46
Q

define Bruton-type agammaglobulinemia

A

a type of congenital immuno deficiency disease

  • inherited disease, most severe of B cell deficiencies.
  • inability to make immunoglobins
  • children (usually boys) experience recurrent bacterial infections but usually resistant to viral, fungal, protozoan infections
47
Q

define graft

A

a transfer of a tissue from one body part to another or from one person to another w/o the transfer to blood supply of the grafted tissue

48
Q

list the different types of grafts and their definitions

A
  • autograft: graft of tissue from one part to another, on same person (no rejection)
  • Isograft: identical twins have same genetic makeup so when skins/organs are transferred their is no immune response
  • allograft: grafts between different people who are not identical twins
  • Xenograft: grafts transplanted between individuals of different species

Microbiology (17 decks)

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