First Aid Immunology -- Lymphocytes

Front 1

Innate Immunity

Back 1

- receptors that recognize pathogens are germline encoded
- response to pathogens is fast and nonspecific
- no memory

Front 2

Adaptive Immunity

Back 2

- receptors that recognize pathogens undergo V(D)J recombination during lymphocyte development
- response is slow on 1st exposure, but memory response is faster and more robust
- has memory

Front 3

T cell differentiation starts in?

Back 3

- Bone marrow
- T cell precursor (bald)

Front 4

After the bone marrow, T cells travel to?

Back 4

Cortex of Thymus:
- Positive Selection -- a T cell receptor, CD8, and CD4 are added to bald precursor
- yield a CD4+CD8+ Tcell

Front 5

After the cortex of the thymus, T cells travel to?

Back 5

Medulla of Thymus:
- Negative Selection -- either the CD8 or CD4 is removed
- yields a CD8+ T cell or a CD4+ T cell

Front 6

After the medulla of the thymus, T cells travel to?

Back 6

Lymph node

Front 7

In the lymph node, CD8+ T cell becomes:

Back 7

Cytotoxic T cell

Front 8

What do Cytotoxic T cells do?

Back 8

kill:
- virus-infected cells
- neoplastic cells
- donor graft cells

Front 9

In the lymph node, CD4+ T cells becomes what via IL-12?

Back 9

Th1 cell (cell-mediated response)

Front 10

In the lymph node, CD4+ T cells becomes what via IL-4?

Back 10

Th2 cell (humoral response)

Front 11

What do Th1 cells make? (2)

Back 11

IL-2 and IFN-γ

Front 12

What cells do Th1 cells activate? (2)

Back 12

Macrophages and CD8+ cells

Front 13

Th1 cells are inhibited by?

Back 13

IL-10

Front 14

What do Th2 cells make? (4)

Back 14

- IL-4
- IL-5
- IL-10
- and helps B cells make antibody (IgE > IgG)

Front 15

Th2 cells are inhibitied by?

Back 15

IFN-γ

Front 16

MHC

Back 16

- major histocompatibility complex
- encoded by Human Leukocyte Antigen (HLA) genes
- present antigen fragments to T cells and bind TCR

Front 17

MHC I Mneumonic

Back 17

HLA I letter:
- A, B, C

Front 18

MHC II Mneumonic

Back 18

HLA II letters:
- DR, DP, DQ

Front 19

MHC I

Back 19

- HLA-A, HLA-B, and HLA-C
- expressed on almost all nucleated cells
- mediates viral immunity
- pairs with β2-microglobulin (aids in transport to cell surface)

Front 20

MHC II

Back 20

- HLA-DR, HLA-DP, and HLA-DQ
- expressed only on antigen-presenting cells (APCs)
- antigen is loaded following release of invariant chain in an acidified endosome

Front 21

What MHC is expressed on almost all nucleated cells?

Back 21

MHC I

Front 22

What MHC is expressed on APCs?

Back 22

MHC II

Front 23

A3 HLA subtype is associated with?

Back 23

Hemochromatosis

Front 24

B27 HLA subtype is associated with?

Back 24

PAIR:
- Psoriasis
- Ankylosing spondylitis
- Inflammatory bowel disease
- Reiter's syndrome

Front 25

B8 HLA subtype is associated with?

Back 25

Graves' disease

Front 26

DR2 HLA subtype is associated with?

Back 26

- Multiple sclerosis
- Hay fever
- SLE (systemic lupus erythematosus)
- Goodpasture's

Front 27

DR3 HLA subtype is associated with?

Back 27

Diabetes mellitus type 1

Front 28

DR4 HLA subtype is associated with?

Back 28

- Rheumatoid arthritis
- Diabetes mellitus type 1

Front 29

DR5 HLA subtype is associated with?

Back 29

- Pernicious anemia → B12 deficiency
- Hashimoto's thyroiditis

Front 30

DR7 HLA subtype is associated with?

Back 30

Steroid-responsive nephrotic syndrome

Front 31

Innate immunity consists of which cells:
(5)

Back 31

- neutrophils
- macrophages
- dendritic cells
- natural killer cells
- complement

Front 32

Adaptive immunity consists of which cells:
(3)

Back 32

- T cells
- B cells
- circulating antibody

Front 33

B cell functions:
(5)

Back 33

- Make antibody
- IgG antibodies opsonize bacteria and neutralize viruses
- Allergy -- type 1 hypersensitivity → IgE
- Cytotoxic (type 3) and Immune complex (type3) hypersensitivity → IgG
- Antibodies cause organ rejection (hyperacute)

Front 34

T cell functions:
(4)

Back 34

- CD4+ (helper) T cells help B cells make antibody and produce γ-interferon (which activates macrophages)
- Kill virus-infected cells directly (CD8+ [cytotoxic] T cells)
- Delayed cell-mediated hypersensitivity (type 4)
- Organ (allograft) rejection (acute and chronic)

Front 35

Natural Killer Cells

Back 35

- use perforin and granzymes to induce apoptosis of virally infected cells and tumor cells
- induced to kill when exposed to a nonspecific activation signal on target cell and/or to an absence of class I MHC on target cell surface

Front 36

Natural Killer Cell activity is enhanced by:
(3)

Back 36

- IL-12
- IFN-α
- IFN -β

Front 37

The only lymphocyte member of the innate immune system?

Back 37

Natural killer cells

Front 38

Helper T cells and T cell glycoproteins

Back 38

Have CD4, which binds to MHC II on APCs


- product of CD and MHC = 8
- CD4 x MHC II = 8

Front 39

Cytotoxic T cells and T cell glycoproteins

Back 39

Have CD8, which binds to MHC I on virus-infected cells


- product of CD and MHC = 8
- CD8 x MHC I = 8

Front 40

CD3 complex

Back 40

- cluster of polypeptides associated with a T cell receptor
- important in signal transduction

Front 41

APCs (3)

Back 41

Antigen Presenting Cells

- macrophage
- B cell
- dendritic cell

Front 42

Macrophage-Lymphocyte interaction

Back 42

- activated lymphocytes release IFN-γ
- activated macrophages release IL-1 and TNF-α
- stimulate one another

Front 43

Effects of Superantigens

Back 43

S. pyogenes and S. aureus


- cross-link the β-region of the T cell receptor to the MHC class II on APCs
- results in the uncoordinated release of IFN-γ from Th1 cells and subsequent release of IL-1, IL-6, and TNF-α from macrophages

Front 44

Effects of Endotoxins/Lipopolysaccharides

Back 44

gram-negative bacteria


- directly stimulate macrophages by binding to endotoxin receptor CD14
- Th cells are NOT involved

Front 45

T and B cell activation

Back 45

2 signals are required for T cell activation and B cell class switching → signal 1 and signal 2

Front 46

Th activation

Back 46

1. foriegn body is phagocytosed by APC
2. foreign antigen is presented on MHC II and recognized by TCR on Th cell (signal 1)
3. "Costimulatory signal" is given by interaction of B7 and CD28 (signal 2)
4. Th cell activated to produce cytokines

Front 47

Tc Activation

Back 47

1. endogenously synthesized (viral or self) proteins are presented on MHC I and recognized by TCR on Tc cell (signal 1)

2. IL-2 from Th cell activates Tc cell to kill virus-infected cell (signal 2)

Front 48

B cell Class Switching

Back 48

1. IL-4, IL-5, or IL-6 from Th2 cell (signal 1)

2. CD 40 receptor activation by binding CD40 ligand on Th cell (signal 2)

Front 49

Which part of the antibody recognizes the antigen?

Back 49

Variable part of L and H chains

Front 50

Which part of the antibody fixes complement?

Back 50

Fc portion of IgM and IgG

Front 51

Heavy chain makes up which portion of antibody?

Back 51

All of the Fc fragment and part of the Fab fragment

Front 52

Light chain makes up which portion of antibody?

Back 52

only part of the Fab fragment

Front 53

Fab portion of antibody

Back 53

- antigen-binding fragment
- determines idiotype: unique antigen-binding pocket --> only 1 antigenic specificity expressed per B cell
- amino terminal

- made up of all of the L chain, part of the H chain (including variable parts of both)

Front 54

Fc portion of antibody

Back 54

- Constant
- Carboxy terminal
- Conplement binding at CH2 (IgG + IgM only)
- determines isotype (IgM, IgD, etc.)

- Fc = lots of C's

Front 55

Antibody diversity is generated by:
(4)

Back 55

1. Random "recombination" of VJ (light-chain) or V(D)J (heavy-chain) genes.

2. Random combination of heavy chains with light chains.

3. Somatic hypermutation (following antigen stimulation).

4. Addition of nucleotides to DNA during "recombination" (see #1) by terminal deoxynucleotidyl transferase.

Front 56

Opsonization

Back 56

Antibodies attach to antigen, coating it and promoting phagocytosis

Front 57

Neutralization

Back 57

Free antibodies coat antigen and prevent bacterial adherence

Front 58

Complement Activation

Back 58

- Antibody activates complement, anhancing opsonization and lysis
- Membrane Attack Complex (MAC)

Front 59

What do mature B lymphocytes express on their surface?

Back 59

IgM and IgD

Front 60

How do B cells change in to plasma cells?

Back 60

Isotype Switching

Front 61

Isotype Switching

Back 61

- how B cells differentiate into plasma cells
- alternative splicing of mRNA
- mediated by cytokines and CD40 ligand

Front 62

What do plasma cells secrete?

Back 62

IgA, IgE, or IgG

Front 63

IgG

Back 63

- main antibody in the secondary (delayed) response to an antigen
- most abundant
- fixes complement
- crosses the placenta -- provides infants with passive immunity
- opsonizes bacteria
- neutralizes bacterial toxins and viruses

Front 64

IgA

Back 64

- prevents attachment of bacteria and viruses to mucous membranes
- does NOT fix complement
- monomer (in circulation) or dimer (when secreted)
- found in secretions (tears, saliva, mucus) and breast milk (known as "colostrum")
- picks up secretory component from epithelial cells before secretion

Front 65

IgM

Back 65

- produces in the primary (immediate) response to an antigen
- fixes complement
- but does NOT cross the placenta
- antigen receptor on the surface of B cells (along with IgD)
- monomer on B cell or pentamer
- shape of pentamer allows it to efficiently trap free antigens out of tissue whil humoral response evolves

Front 66

IgD

Back 66

- unclear function
- found on the surface of many B cells and in serum

Front 67

IgE

Back 67

- binds mast cells and basophils
- cross-links when exposed to allergen --> mediating immediate (type I) hypersensitivity --> through the release of inflammatory mediators such as histamine
- mediates immunity to worms by activating eosinophils
- lowest concentration in serum

Front 68

Ig Epitopes

Back 68

- allotype (polymorphism) -- Ig epitope that differs among members of the same species
- can be on the light chain or heavy chain

- "ALLotypes represent different ALLeles"

Front 69

Isotypes

Back 69

- ie. IgG, IgA, etc.
- Ig epitope common to a single class of Ig (5 classes, determined by heavy chain)

- Isotype = iso (same) --> common to the same class

Front 70

Idiotype

Back 70

- specific for a given antigen
- Ig epitope determined by antigen-binding sites

- Idiotype = idio (unique) --> hypervariable region is unique

Front 71

Thymus-Independent Antigens

Back 71

- antigens lacking a peptide component
- cannot be presented by MHC to T cells
- stimulate release of IgM antibodies only
- do not result in immunologic memory

- ie. lipopolysaccharide from cell envelope of gram-negative bacteria and polysaccharide capsular antigen

Front 72

Thymus-Dependent Antigens

Back 72

- antigens containing a protein component
- class switching and immunologic memory --> occur as a result of direct contact of B cells with Th cells (CD40-CD40 ligand interaction)
- causes release of IL-4, IL-5, and Il-6

- ie. conjugated H. influenzae vaccine