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Flashcards in Immunology Deck (69):
1

DAF

Cleaves C3b and Bb to prevent the activation of C3 convertase

2

Factor 1

Cleaves C3 making it protealytically inactive

3

CD59

Blocks the formation of the MAC by binding to C9

4

C1INH

Inhibits C1r and C1s from cleaving any further complements and activating the cascade

5

V(D)J Recombination

1. D and J genes reassemble to form DJ segment

2. V and DJ combine to form VDJ segment(
-codes the variable domain of IgH or TCR-B

*RAG needed for recombination to occur, must cleave the RSs for Step 1 to occur

6

RAG Genes

Recombination Activation Genes recognize Recombination Signal Sequences (RSS) and act as an endonuclease to all recombination to occur

7

P-nucleotides

Added to hairpin VDJ structures by DNA Polymerase; produces BLUNT ENDS

*Number of n-nucleotides is variable

8

N-nucleotides

Added to blunt ends on VDJ-structures; sequence of N-nucleotides is random

9

Terminal Deoxynucleotidyl Transferase

Adds N-nucleotides to the VDJ-structure

10

How are the variable (VDJ) and constant (C) domains joined together?

RNA splicing

11

Combinatorial Diversity

Introduces Ag-receptor diversity because any IgH chain can pair with any IgL chain OR any TCR-B chain can pair w/ any TCR-A chain; also includes VDJ recombination

*Junctional diversity still introduces more diversity

12

Pro-B Cell

Expression of Rag proteins first appears

IgH gene arrangement occurs

CD10 and CD19 appear

*Cytokines promote proliferation (Ag dependent); ensures large pool for IgH chain diversity

13

Pre-B Cell

Expression of IgH chain

Assembly of Pre-B cell receptor
-consists of IgH, surrogate light chains V pre-B and delta-5, Iga, and Igb



14

Functions of Pre-B cell

1. Allelic exclusion

2. Provide signals for proliferation of pre-b cells

3. Stimulate IgL rearrangement

4. Suppress surrogate light chain expression

15

Productive kappa rearrangement on Pre-B cells (Isotypic Exclusion)

Will show no lambda rearrangement

16

X-linked agammagloblulinemia

Mutation in Btk gene causes a defect in pre-BCR mediated survival of Pre-B cells

17

Allelic Exclusion

The expression of only one allele of the IgH chain from either maternal or paternal origin

18

Immature B-cells

Expression of a BCR w/ IgM

Weakly self-reactive BCR= signal for survival

Rag protein expression ends

19

B1 B cells

In adults, reside in peritoneum and mucosal sites

Contain only surface IgM

Spontaneous production of IgM

Reactive to microbial polysaccharides and lipids

Self-renewing capability

20

Marginal zone B2 cells

Contains surface IgM only

Produce abs against polysaccharides

T-cell independent immune responses

21

Follicular B2 cells

Reside in B cell follicle

Contain surface IgM AND IgD

Survival dependent on BAFF/BlyS

T-cell DEPENDent immune responses

*Major B2 B cells

22

Function of Thymus in T-cell development

Provides:

IL-7 for proliferation of progenitors

Chemokines to guide developing T-cell movement towards medulla

MHC molecules for positive/negative selection

23

DiGeorge Syndrome

Congenital absence of a thymus resulting in low numbers of T-cells

=>frequent infxns

24

Pro-T cell

(CD4-, CD8-)

Expresses proteins for recombination (Rag, TDT)

TCR-B rearrangement occurs

25

SCID

Mutations in the y-common chain of the IL-7 receptor lead to a block in T-cell development

26

Pre-T Cells

(CD4-, CD8-)

Expression of pre-TCR and assembly of B, A, and CD3 subunits

Signals provide:

Inhibition of further TCR-B rearrangement (which is called?)

Initiation of TCR-A rearrangement

*Largest proliferation of T-cell development occurs here

27

TCRa

Has NO allelic exclusion, therefore, a TCR can express 2 alpha chains

28

Double positive thymocytes

(CD4+, CD8+)

Expression of TCR

Weakly reactive to MHC-self peptides

*Negative selection of strongly reactive, death to non-reactive

29

Single Positive Thymocytes

Derived from double-positive; are formed from interactions w/ MHC class I or II molecules

*Mature in thymic medulla

30

CR2 Complex

Co-activator complex found on B-cells that consist of CD 81, CD 19, and CD20 that bind to C3d to promote further activation of B-cells

31

How are BCRs turned off?

Via CD22 or excess Ag binding to to Ig and then binding to FcyR

32

CD5+ B-cells

T-cell indepenent B-cells that respond to repeating polysaccharide sequences on bacteria and produce primarily an IgM, non-specific response

33

Extrafollicular Focus

The meeting of a Th2 cell and an APC B-cell in the para-cortical jnxn where these cells proliferate the response of each other

*Most B-cells become short-lived plasma cells

34

Cognate Interactions

Interactions b/w CD40L on Th2 cells and CD40 on B-cells

=>Drives Th2 cells to produce IL-4, IL-5, and IL-6

35

B-cell signals (1-3)

1= Ag binding to BCR

2= Cd40 binding to CD40L

3= B7-CD28

36

AID

Activation Induced Deaminase

Allows for the rearrangement of the constant region of genes giving rise to Isotype Class Switching in activated B-cells

37

Somatic Hypermutation

(Affinity Maturation)

B-cells go thru mutations in their receptors that lead to high-affinity binding with their antigen

-If low affinity, cell undergoes apoptosis

38

Whole-cell inactivated vaccine

Polio

39

Subunit inactivated vaccine

Hepatitis B

40

Polysaccharide inactived vaccine

Pneumococcal

41

Live attenuated vaccines

Provide T-cell and antibody immunity

42

Antigenic Sin

The body only recognizes the current immunodominant epitope, therefore, if that changes, then the body treats the pathogen as a new, unrecognized foreign invader

43

Functional part of an antibody

Fc portion

44

Idiotype

Ab determinant defined by the variance of the epitopes; can differ inside a single individual

45

Molecular basis of the gram stain

Stains the peptidoglycan wall of Gram + bacteria

46

Bacteria sensitive to lysozyme?

Gram +; cleavage of the B-1,4 linkages

47

Effects of MDP

1. Pyrogen

2. Mitogen

3 Somnagen

4. Adjuvant

48

Clinical Effects of LPS

Somnagen

Pyrogen

Leukopenia

DIC

Hypotension

49

TLRs

Can be present on innate immune cell membranes or on the endoplasmic membrane and stimulate the release of NFkB

=>Production of cytokines

50

NOD-like receptors

Detect bacterial signatures inside of cells

51

RIG-like receptor

Detects viral signatures

52

CR1

Receptor for C3b and detects opsonized pathogens

*Found on many RBCs

53

Lysosomal enzyme that digests bacteria

NADPH; generates oxygen radicals

54

Lactoferrin

Released by neutrophils and competes w/ invading microbes for iron

55

IFN-a and IFN-b

During viral infection, these bind to uninfected cells and prevent viral replication

56

NK cells

Macrophage secretion of IL-12 activates these cells and stimulates the production of IFN-y which will cause NK cells to eliminate infected cells

*Form of positive feedback

57

IL-6

Released by macrophages and T-cells; leads to the hepatic synthesis of acute phase proteins

58

CXCL-8

IL-8

Acts on macrophages as a chemo tactic molecule

59

IL-12

Activates NK cells and induces the differentiation of CD4+ cells into Th1 cells

60

Dangers of TNF-a

Can cause the wasting of cells leading to cachexia

*Normally induces fever in the brain and acute phase protein synthesis in the liver

61

Invariant Chain

Binds to the MHC II complex after being synthesized in the rough ER; prevents binding of peptides

62

CLIP protein

Cleaved invariant chain that binds to MHC II proteins preventing pathogenic peptide products from binding until the endocytic vesicle fuses w/ the outer membrane

63

Calnexin

Binds to MHC I molecules in the ER until B-2 chain can bind

64

TAP

ER channel that transports cytosolic peptide fragments made from proteasomes to bind w/ the MHC/calreticulin complex

65

CCR7

Receptor on dendritic cells activated by inflammation in the tissues; leads to dendritic cells becomes APCs

66

EBF, E2A, Pax5

Stimulate the differentiation into a Pro-B cell

67

BAFF2/BlyS

Proteins necessary for the survival of Follicular B2 B-cells

68

IL-22

Secreted by Th17 cells to activate epithelial cells to secrete anti microbial substances; assoc. w/ IL-17 which will increase inflammation

69

Allorecognition

T-cells now recognize foreign MHC and can produce a response when they present AG