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MEDLABS - Immunology > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

Immunogen

A

macromolecules capbale of triggering an adaptive immune response by inducing the formation of antibodies or sensitized T cells in an immunocompetent host
can specifically react with antibodies or sensitized T cells

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2
Q

Antigen

A

a substance that reacts with an antibody or sensitized T cells but may not be able to evoke an immune response in the first place

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3
Q

Relationship of immunogen to antigen

A

Immunogen = antigen; antigen =/= immunogen

Immunogen is basically a type of antigen; angiten is a broader term

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4
Q

Biological properties of an individual that influence the immune response

A 
age (middle aged = best)
overall health (nourishment/fatigue/stress) 
dose (quantity of immunogen)
route of inoculation (IV, ID, SubQ, oral) 
genetic capacity (MHC)
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5
Q

Immunogenicity

A

the ability of an immunogen to stimulate a host response
depends on macromolecular size, foreigness, chemical composition/molecular complexity, ability to be processed and presented with MHC molecules

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6
Q

Immunogenicity characteristics

A

molecular weight - the bigger the beter (response)
foreigness - allows distinguishing self from nonself
chemical composition/chemical complexcity - longer/larger chains of proteins/amino acids (more complex shapes)
ability to be processed - must be degraded and presented to MHC to create a response

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7
Q

Epitope

A

key portion of the immunogen (determinant site)

molecular shapes or configurations that are recognized by B/T cells

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8
Q

Linear/conformational epitope

A

LE - (sequential) amino acids following one another on a single chain
CE - One+ chains folded to make linear and conformational epitopes

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9
Q

Antigen-presenting cell (APC)

A

cell that degrades and presents immunogens for immune response

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10
Q

Haptens

A

nonimmunogenic materials that, when combines with a carrier, create new antigenic determinants
small substances that cannot create a rxn on their own
categorized as antigens (not immunogens)
hapten + carrier = precipitation and agglutination reaction

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11
Q

Examples of haptens

A

Catechols (H) (poison ivy) + tissue proteins of skin -> rxn of skin
Penicillin (Normal body proteins + hapten)

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12
Q

Adjuvant

A

a substance administered with an immunogen that increases the immunce response in order to provide immunity to a particular disease help make immunization more effective protect immunogens from degradation + allow a longer response time (larger immune response)

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13
Q

Autoantigens

A

antigens that belong to the host do not evoke an immune response under normal circumstances

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14
Q

Autoimmune Disease

A

when autoantigens become self reactive to the body

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15
Q

Alloantigens

A

antigens from other members of the host’s species and are capable of eliciting an immune response important to tissue transplantation and blood transfusions

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16
Q

Heteroantigens

A

antigens from other species (other animals, plants, or microbes)

17
Q

Heterophile anitgens

A

heteroantigens that exist in urelated plants or animals but are either identical or closely related in structure so that antibody to one will cross-react with antigen of the other
(blood group A/B antigens and bacterial polysaccharides)

18
Q

SRBCs

A

Sheep red blood cells important to the development/study of heterophile antigens

19
Q

MHC location and function

A
  • located on all nucleated cells in the body
  • function in determining self/non-self, can function as antigens, activate T cells
  • once called HLA - Human Leukocyte antigens
20
Q

MHC system

A
  • most polymorphic system found in humans

- code for proteins immune recognition/ diverse immunogens

21
Q

MHC gene coding

A
  • found on short arm of chromosome 6

- 3 categories/ classes

22
Q

MHC class 1

A
  • found at 3 loci; A,B,C

- only one gene coding for each particular molecule

23
Q

MHC Class 2

A
  • found in the D region
  • loci are DR,DQ, DP
  • one gene codes for alpha chain; 1+ gene(s) code for beta chain
24
Q

MHC Class 3

A
  • Found between Class 1 and class 2 regions on chromosome 6

- codes for C4A, C4B, C2, and B complement proteins, Cytokines and tumor necrosis factor

25
Q

Roles of MHC classes

A

MHC class 1 and 2 - involved in antigen recognition (influence the antigens Tcells respond to)

MHC class 3 - secreted proteins that have an immune function (not expressed on cell surfaces

26
Q

Alleles

A

alternate forms of a gene that code for slightly different varieties of the same product

27
Q

Polymorphic system (MHC)

A

many possilbe alleles at each location at each loci
(HLA-A) 2,013
(HLA-B) 2,605
(HLA-C) 1,551
Low probability that 2 individuals will express the same MHC molecules

28
Q

characteristics of MHC genes

A
  • codominant (all alleles expressed)
  • Haplotype inheritance (closely linked, genes inherited together)
  • each inherited chromosomal region has a package of genes for A,B,C,DR,DP,DQ
  • One haplotype inherited from each parent
29
Q

expression of MHC class 1

A
  • on all nucleated cells
  • highest on lymphocytes and myeloid cells
  • low/undetectable on liver hepatocytes, neural cells, muscle cells and sperm
30
Q

Structure of Class 1 MHC molecules

A

Glycoprotein dimer of two noncovalently linked polypeptide chains
alpha chain (heavier), folded into 3 domains, inserted in the cell membrane, hydrophobic
Beta 2- microglobulin (lighter) encoded by one gene on chromosome 15 (not polymorphic)

(this is the same in every Class 1 molecule, essential for folding of alpha chain, no cell membrane penetration

31
Q

expression of MHC class 2

A

found on APCs (B lymphocytes, monocytes, macrophages, dendritic cells, thymic epithelium)

32
Q

Structure of Class 2 MHC molecules

A

DP,DQ,DR - 2 noncovalently bound polypeptide chains (heterodimers)
DR expressed the most (accounts for 1/2 of all Class 2 molecules)
DR beta - most highly polymorphic

33
Q

Antigen presentation

A

process by which degraded peptides within cells are transported to the plasma membrane where T cells can then recognize them

34
Q

MHC classes present to which T cells

A

Class 1 molecules peptides synthesized withine the cell to CD8 T cells (viral, tumor, parasitic antigens)

Class 2 molecule present exogenous antigen to CD4 T cells (bacterial infections, extracellualr pathogens)

35
Q

Class 1 MHC-peptide interaction

A

Endogenous pathway of antigen presentation

synthesized in ER and bind peptides from where they are bound on the ER
forms a complex and moves to the cell surface where it can be recognized by T cells
CD8+ T cells produce cytokines that cause lysis of the entire cell

36
Q

Proteasomes

A

large cytoplasmic complexes of the proteases

cleave peptides for delivery to class 1 molecules

37
Q

Transporters associated with antigen processing

A

proteins responsible for ATP-dependent transport of peptides to class 1 molecules

most efficient with 8-16 amino acids in size

38
Q

Class 2 MHC - peptide interaction

A

synthesized in ER (+invariant chain), transported to endosomal compartment where they can bind to peptides
binds to peptides of 13-18 amino acid residues
once bound, molecule is transported to cell surface for recognition by T cells
CD4+ recruits and triggers B-cell response

39
Q

Clinical importance of MHC molecules

A 
Ankylosing spondylitis
Celiac disease
Rheumatoid arthritis 
Type 1 diabetes 
(autoimmune diseases) 
Vaccine sensitivity

MEDLABS - Immunology (24 decks)

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