Lecture 1: Cellular and Innate Immunity Flashcards

1
Q

What kind of cell is this?

Where is it located?

What are its functions?

From which cell type is it derived?

Cellular or innate immunity?

A

Macrophages are large, mononuclear phagocytic cells

Location: in most tissues

Functions: phagocytosis, antigen presentation

Derived from blood monocytes (2-6% of WBCs)

Innate immunity

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2
Q

What kind of cell is this?

Where is it located?

What are its functions?

Cellular or innate immunity?

A

Neutrophils (polymorphonuclear neutrophilic leukocytes) are phagocytic cells

They comprise 50-60% of WBCs (most abundant WBC)

Function: bactericidal; enter infected tissues to engulf and kill extracellular pathogens

Innate immunity

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3
Q

What kind of cell is this?

Where is it located?

What are its functions?

Cellular or innate immunity?

A

Eosinophils (1-4% of WBCs)

Function: kill Ab-coated parasites that are too large for phagocyte digestion; also allergic responses

Innate immunity

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4
Q

Top and bottom:

What kind of cell is this?

Where is it located?

What are its functions?

Cellular or innate immunity?

What are similarities and differences between these 2 cell types?

A

Top: Basophils (0.5-1% of WBCs)

Location: blood

Function: antiparasitic (esp. helminths), allergic responses

Bottom: Mast cells

Location: connective tissues

Function: antiparasitic (esp. helminths), allergic responses

Innate immunity

Same function, different location and cellular structure

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5
Q

What kind of cell is this?

Where is it located?

What are its functions?

Cellular or innate immunity?

A

Natural killer (NK) cell

* kills some virus-infected cells and some tumor cells

Innate immunity

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6
Q

What type of cell is this?

What are its functions?

Is this involved in cellular and/or innate immunity?

A

Dendritic cells (DC)

Functions: Antigen uptake in peripheral sites, Ag-presentation to T cells

* bridge innate and adaptive immune responses

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7
Q

Which specialized cells function in allergic responses? What about anti-parasite responses?

A

Anti-parasitic and allergic responses

* Mast cells (CT): histamine release

* Basophils (0.5-1% WBC) (blood): histamine release

* Eosinophils (1-4% WBC): kill parasites that phagocytes cannot ingest; secretions (ex. toxic to helminths), allergic responses

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8
Q

Which is the most abundant WBC?

A

Neutrophil (50-60% WBC): polymorphonuclear neutrophilic leukocytes

Function: phagocytosis

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9
Q

Which specialized cells participate in phagocytosis?

A

Phagocytosis

Neutrophils (50-60% WBC) (polymorphonuclear neutrophilic leukocytes)

* antibacterial function

* enter infected tissues

* engulf/kill extracellular pathogens

Macrophages (from monocytes)

* large, mononuclear

* in most tissues

* Ag presentation

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10
Q

What kind of cell is this?

Where is it located?

What are its functions?

Cellular or innate immunity?

A

Lymphocytes (25-40% WBC)

in the blood

~20% B cells, 80% T cells

Humoral immunity: Ag-specific Ab produced by activated B cells (plasma cells)

Cell-mediated immunity (CMI): Ag-specific T cell responses

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11
Q

What is clonal selection?

A

Clonal selection results in the expansion of Ag-specific B and T cell clones.

A single progenitor cell produces many lymphocytes, each with a different specificity.

Clonal selection then removes self-reactive immature lymphocytes (clonal deletion).

This results in a pool of mature naive lymphocytes.

Proliferation and differentiation then produce effector cells and memory cells (T and B cells).

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12
Q

polyclonal response

A

Antibody responses are polyclonal.

A single antigen may have several epitopes (Ag-recognition sites) which recruit different antibodies.

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13
Q

What are the primary lymphoid organs (adults)? What happens there?

A

Primary Lymphoid Organs (Where the cells originate/begin development)

* Bone marrow (B cells)

* Thymus (T cells)

These are sites of lymphocyte development and where Ag-specific receptor is acquired

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14
Q

What are the secondary lymphoid organs (adults)?

When do cells migrate to the secondary lymphoid organs?

What happens there?

A

Secondary lymphoid organs

* adenoid

* tonsil

* lymph nodes

* spleen

* Peyer’s patches

Function: lymphocytes encounter/respond to Ag

  • Many mature B and T cells migrate from bone marrow and thymus through blood to secondary lymphoid tissues
  • These sites trap Ag and facilitate Ag contact with lymphocytes
  • Ag recognition by lymphocytes –> proliferation/differentiation of B and T cells: immune response
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15
Q

Do you have B and T cells with Ag-specific receptors for tetanus? SARS?

A

Yes – Ag recognition is not pathogen exposure-dependent

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16
Q

What are the 3 phases of an immune response to infection?

A

1. Innate immunity (immediate, 0-4 h)

* infection –> nonspecific effector recognition –> remove pathogen

2. Early induced innate response (4-96 h)

* recruit effector cells –> innate cell-PRR (ex. TLR4) recognizes PAMP (ex. bacterial LPS) –> remove pathogen

innate cell-PRR (ex. TLR4) recognizes PAMP (ex. bacterial LPS) –> remove pathogen

3. Adaptive immune response (late: >96 h)

* transport Ag to lymphoid organs –> recognition by naive B and T cells –> clonal expansion/differentiation to effector cells –> remove pathogen

17
Q

What are the 6 types of leukocytes?

What’s another name for a leukocyte?

A

Leukocytes (WBC)

* dendritic cells (DC)

* macrophages (M-phi)

* natural killer cells *NK)

* neutrophils

* mast cells, basophils

* eosinophils

18
Q

Compare and contrast innate and adaptive immunity

A
19
Q

What is MALT?

A

Secondary lymphoid organs

  • mucosa-associated lymphoid tissue (MALT)
    • tonsils
    • Appendix
    • Peyer’s patches: lymphocyte clusters along lining of small intestin
20
Q

What are GALT and BALT?

A

Linings of digestive, respiratory, genitourinary tracts (secondary lymphoid organs)

GALT (gut-associated lymphoid tissues)

BALT (bronchus-associated lymphoid tissues)

21
Q

What are Fab regions? How many does an antibody have? How do you separate Fab regions from the rest of the antibody?

A

An Ab has 2 Fab regions

1 Fab = 1 complete L + part of 1 H = 1 Ag binding site

Papain + Antibody –> 2 Fab + 1 Fc

22
Q

What are Fc regions? What are their function?

A

an antibody has 2 Fc regions (S-S bond connection of heavy chains)

  • determines effector function(s) to activate by Ag-Ab complex
23
Q

What are heavy chains? What do they do? How many does an antibody have?

What is a hinge region?

A

An antibody monomer has 2 heavy chains (H).

Antibody classes (IgG, -A, -M, -E, -D) are determined by H-chain constant region

The link between paired H chains is called the flexible region (hinge region)

24
Q

What are light chains?

A
  • An Ab monomer has 2 light chains (L)
    • each Ab has one of 2 isotypes: Kappa (k) and lambda (l)
    • humans: 60% k and 40% l chains
25
Q

What does pepsin digestion of an Ab yield?

A
  • Pepsin: 2 Fab
  • Fc region is destroyed
26
Q

What are variable regions?

A

Variable regions (V regions)

  • VH (heavy chain) and VL (light chain)
  • N-terminal ends
  • impart Ag specificity
  • Ag binding site = 1 VH + 1 VL
27
Q

What are constant regions?

A
  • Constant regions (C regions): CH (heavy) and CL (light) (shared by many Ab)
28
Q

What colors do these stain?

  • Neutrophils
  • Basophils
  • Eosinophils
A
  • Neutrophils: pale lilac
  • Basophils: dark blue
  • Eosinophils: red
29
Q

Innate or adaptive immunity?

  • Rheumatoid arthritis (RA)
A
  • Rheumatoid arthritis (RA): humoral and cell-mediated immunity; autoreactive T cells, autoantibodies
30
Q

Innate or adaptive immunity?

AIDS

A

AIDS: adaptive (cellular and humoral) immunity: CD4+ TH cell destruction is also an adaptive immunity defect; TH is necessary for B cell (humoral) responses, too

31
Q

Innate or adaptive immunity?

Cystic fibrosis

A

Cystic fibrosis (CFTR) defect – dysregulated innate immunity; neutrophil and macrophage function and airway mucocilliary clearance system impaired –> lung disease

32
Q

Which cells are granulocytes? What are they?

A
  • Granulocytes: lots of cytoplasmic granules
    • Neutrophils: stain pale lilac
    • Basophils: stain dark blue
    • Eosinophils: stain red
    • Dendritic cells (DC): in most tissues incl. lymphoid tissue
      • Take up/transport Ag to peripheral lymphoid organs –> activate T cells
33
Q

What are CD4+ T cells? What is another name for them? What do they do?

A
  • CD4+ T cells (Th) produce cytokines
34
Q

What do CD8+ T cells do? What is another name for them?

A

CD8+ T cells (Tc) recognize, kill pathogen infected cells/tumor cells