Immune Response Flashcards

1
Q

Describe mucosa-associated lymphoid tissue (MALT)

A
  • Layer of lymphoid tissue at mucosal layers in which lymphocytes are found
  • Organises response to antigens entering mucosal tissue
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2
Q

What are the cellular components of the innate immune system?

A
  • ANTIGEN PRESENTING CELLS - Dendritic cells/monocytes/macrophages
  • GRANULOCYTES
  • NK and MAST cells
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3
Q

What are the two types of adaptive immunity?

A
  • HUMORAL - mediated by antibodies secreted by B lymphocytes
  • CELL MEDIATED - T lymphocytes activate macrophages or kill infected cells
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4
Q

What immune response do intra- and extracellular pathogens induce?

A

EXTRACELLULAR - humoral
INTRACELLULAR - cell-mediated

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5
Q

Describe humoral immunity. PART 1

A
  • B cells formed in bone marrow
  • Receptors to which antigens can attach
  • Produce antibodies
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6
Q

Describe humoral immunity. PART 2

A
  • Antigen recognised, engulfed and digested by B cell
  • Displays antigen fragments bound to MHC molecules
  • Attracts T cells which secretes cytokines to help B cells multiply and form antibody-producing plasma cells or memory cells
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7
Q

What are antigens?

A
  • Substance triggering immune response
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8
Q

Describe the two antigen properties.

A
  • IMMUNOGENICITY - ability to induce immune response
  • SPECIFICITY - ability to react with effector mechanisms of immune system
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9
Q

What are epitopes?

A

Region of antigen interacting with antibody

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10
Q

What are antibodies and what do they do?

A
  • Glycoproteins produced in response to antigens
  • Activate complement system
  • Directly attack pathogens
  • Inactivate toxins produced by bacteria
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11
Q

Outline antibody structure.

A
  • 2 heavy and 2 light Ig chains held by disulfide bonds
  • Each chain has a variable region - attaches to specific antigen
  • Constant domain - determines class and function
  • FAB domain - region binds to antigens
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12
Q

What is the Fc domain?

A
  • Important for interaction betwen antibodies and phagocytes
  • Promotes phagocytosis
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13
Q

Describe IgM.

A
  • Third most abundant
  • Main activator of complement system
  • Expressed on surface of B cells
  • Produced first during primary response
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14
Q

Describe IgG

A
  • Most prevalent class of antibody in serum
  • Expressed on surface of mature B cells
  • Secreted in high quantities in secondary immune response
  • Found in blood/tissue/crosses placenta from mother to fetus
  • Activates complement proteins/opsonises antigens/enhancement of phagocytosis
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15
Q

Define IgA

A
  • Second most common human immunoglobulin
  • Most common in secretions e.g saliva
  • Resistant to digestion - activates complement pathway when aggregated
  • Defends against toxins through body surfaces with mucous membrane
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16
Q

Describe IgD

A
  • Role in antigen stimulated lymphocyte differentiation
  • Helps B cells mature
  • Acts as B cell membrane receptor on surface of B lymphocytes
17
Q

Describe IgE

A
  • Least abundant Ig in serum
  • Triggers allergic reactions - bind to and activate basophils and mast cells which releases histamines in response to allergens
18
Q

Describe the B cell response in the primary immune response.

A
  • Antigen attaches to BCR
  • Some B cells become memory cells and some become plasma cells
  • Plasma cells produce antibodies specific to antigen
  • IgM produced - switched to IgG
19
Q

Describe B cell response in secondary immune response

A
  • Memory B cells rapidly recognise antigen and produce antibodies with higher affinity for specific epitopes
  • Greater antibody levels