Exam 2: Genetics of the Immune Systems

Question 1

antigen

Answer 1

molecules that elicit an immune rxn; produced from foreign bodies and may be proteins, carbohydrates, nucleic acids, or lipids. may also be pollen, pathogens, or spores

Question 2

antibody

Answer 2

proteins that bind to antigens and mark them for destruction by phagocytic cells

Question 3

the organization of the immune system (3)

Answer 3

1. humoral immunity
2. cellular immunity
3. clonal selection

Question 4

humoral immunity

Answer 4

the production of antibodies by B cells; targets

the cells producing circulating antigens in blood/lungs for destruction by macrophages

Question 5

cellular immunity

Answer 5

depends of T cells; directed against cells infected w/ a pathogen and expressing the pathogen’s antigen on host cell surface

Question 6

clonal selection

Answer 6

primary response, memory cells, secondary response

Question 7

an immune response to a specific antigen is produced through

Answer 7

clonal selection

Question 8

immunoglobulins aka _ are _

Answer 8

aka antibodies are glycoproteins produced by white blood cells; 4 polypeptide chains- 2 light and 2 heavy chains that combine to form a Y-shaped structure (disulfide bonds are important for 3D structure)

Question 9

generation of antibody diversity

Answer 9

somatic recombination; break in DNA and reshuffling of domains (genes encoding Ab segments) to produce a variety of segmental combinations (also error/mutations).

Question 10

neutralisation

Answer 10

category of antibody action; neutralizing Abs block parts of the surface of a bacterial cell/virion to rendent its attack ineffective

Question 11

agglutination

Answer 11

category of Ab action; Abs glue together foreign cells into clumps that are attractive targets for phagocytosis

Question 12

preciptiation

Answer 12

category of Ab action; Abs glue together serum-soluble antigens, forcing them to precipitate out of soln in clumps that are attractive targets for phagocytosis

Question 13

complement activation

Answer 13

category of Ab action; (fixation) Abs that are latched onto a foreign cell encourage complement to attack it with a membrane attack complex, which leads to lysis of foreign cell and inflamm response

Question 14

t/f: Ab diversity: millions of possible combination that can respond to infinite possible antigens

Answer 14

true

Question 15

somatic recombination shuffles

Answer 15

the variable region segments (~35 of these)

Question 16

a T-cell receptor is composed of

Answer 16

two polypeptide chains, each having a variable and constant region

Question 17

T-cells are activated by

Answer 17

binding both to a foreign antigen and to a histocompatibility antigen on the surface of a self-cell (MHC)

Question 18

the macrophage breaks open

Answer 18

stimulating additional response (lysis)

Question 19

organ transplant requires a _

Answer 19

genetic match; tissue itself is limiting factor in organ donors

Question 20

immune rejection:

Answer 20

1. MHC antigens: greater the mismatch, the stronger the immune rejection
2. ABO red blood cell antigens also important

Question 21

the major fcn of MHCs is to

Answer 21

bind to peptide fragments derived from pathogens and display them on the cell surface for recognition by the appropriate T-cells

Question 22

immune rejection is partially inhibited by

Answer 22

drugs

Question 23

the most important genes deciding the fate of a transplanted cell, tissue, or organ belong to the

Answer 23

MHC; MHC region occurs on chromosome 6

Question 24

the MHC is a set of

Answer 24

cell surface molecules encoded by a large gene family which controls a major part of the immune sys in all vertebrates (highly conserved)

Question 25

in organ transplantation, _ immunity is considered the main response exerted on the transplanted tissue, since the principal target is the MHC molecules expressed on the surface of donor cells

Answer 25

adaptive immunity

Question 26

autoimmune diseases:

Answer 26

inappropriate behavior/activation of the immune sys; the immune sys sometimes has difficulty distinguishing appropriate target proteins

Question 27

graves disease/Hashimoto thyroiditis

Answer 27

autoimmune; tissue attacked is thyroid gland

Question 28

rheumatic fever

Answer 28

autoimmune; tissue attacked is heart muscle

Question 29

systemic lupus erythematosus

Answer 29

autoimmune; tissue attacked is joints, skin, and other organs

Question 30

rheumatoid arthritis

Answer 30

autoimmune; tissue attacked is synovial joints (chronic inflamm and human leukocyte antigen locus)

Question 31

insulin-dependent diabetes mellitus (diabetes type I)

Answer 31

autoimmune; tissue attacked is insulin-producing cells in pancreas

Question 32

multiple sclerosis

Answer 32

autoimmune; tissue attacked is myelin sheath around nerve cells

Question 33

how is immune-mediated injury to the pancreatic beta cells mediated?

Answer 33

antigen (autoantigen) binds to a groove in MHC on antigen presenting cells that allows the antigen to be presented to antigen receptors on T-cells which initiates the immune-mediated injury

Question 34

what is autoantigen epitope spreading in T1DM?

Answer 34

as the severity of symptoms associated with T1DM increases over time, so does the number of autoantigens (time causes epitopes to be recognized and targeted)

Question 35

first degree relative and T1DM

Answer 35

20% aggregates in families; mom/dad/bro/sis share half DNA with them and have a higher chance of developing diabetes if they do bc are closely related to these indivs (genetic contribution to T1DM)

Question 36

why is a farming environment protective against developing asthma, hay fever, and atopic sensitization in children

Answer 36

the hygiene hypothesis proposed to explain how in westernized countries, stable intestinal micoflora, high antibiotic use, and good sanitation have a higher risk to allergic disorders compared to developing countries with a rural homes and livestock, transient intestinal microflora-variable, low antibiotic use, and poor sanitation are non-allergic and at low risk

Question 37

mutations in IL10RA

Answer 37

• produced by many cell types
• broad anti-inflamm fcn
• mutations cause IBD
• testing for gene not available in US
• bone marrow transplant (carries risk of death)

Question 38

compound heterozygotes

Answer 38

1 mutation form mom and dad (1/4 chance of getting mutation from parent)

Question 39

Somatic recombination shuffles the _ using specific _ that…

Answer 39

Shuffles the variable region segments using specific proteins that direct somatic recombination using specific flanking seqs

Question 40

Recombination is prone to

Answer 40

Error often altering the reading frame

Question 41

Light and heavy chains are _ arranged and light and heavy chains can associate in _

Answer 41

Are similarly arranged and light and heavy chains can associate in all possible combinations

Question 42

_ mutation in this region (variable region segments) adds diversity

Answer 42

Somatic hyper-mutation