Chapter 13: Failures Of The Body's Defenses

Question 1

Pathogens are under great pressure to evolve mechanism to ______, __________, ________, __________, etc. our immune system.

Answer 1

• evade
• overcome
• trick
• suppress

Question 2

Sometime our own bodies fail us, due to __________ genetic or ____________ stresses to the immune system that give the pathogen an upper hand.

Answer 2

• inherited

- environmental

Question 3

Evasion and subversion of the immune system by pathogens

Answer 3

• we have complex responses to pathogens that involve many cellular/molecular interactions between the bug and our immune system
• pathogens can target any of these stages of interaction for its own benefit

Question 4

Genetic Variation within some species of pathogens prevents effective long-term immunity

Answer 4

• protective immunity towards Streptococcus pneumoniae is serotype-specific
• there are about 90 strains of this bug
• they are called serotypes because antibodies are used to differentiate them

Question 5

Mutation and recombination allow influenza virus to escape from immunity

Answer 5

• evolution of new influenza variants by antigenic drift

- they escape immunological memory

Question 6

Antigenic Drift

Answer 6

• causes relatively mild and limited disease epidemic due to point mutation in the gene (hemaglutinin) of the influenza virus
• less worse

Question 7

Antigenic shift

Answer 7

• can cause pandemics
• virus is structurally quite different from its predecessor and can infect almost everyone
• human influenza virus recombines with another virus on a third host

Question 8

Trypanosomes use _________ rearrangement to change their surface antigens

Answer 8

• causative agent of sleeping sickness rearranges its surface glycoprotein antigens (VSG)
• antigenic variation by African trypanosomes allows them to escape from adaptive immunity

Question 9

Herpes viruses persist in human hosts by hiding from the immune response

Answer 9

• herpes simplex virus can become dormant in sensory neurons
• when conditions are right, they come out from the latent state from the trigeminal ganglion via the axon and infect epithelial cells of the lips = cold sore blister

Question 10

Mycobacterium tuberculosis

Answer 10

• prevents fusion of lysosome with the phagosome

- escapes destruction by the macrophages and can hide in the macrophages

Question 11

Treponema pallidum

Answer 11

• causative agent of syphilis

- evades specific antibody by coating itself with human proteins

Question 12

Viruses are great burglars

Answer 12

• in their environment some stole receptors, etc. to neutralize the ligand and intracellular pathways

Question 13

Bacterial super-antigens stimulate a massive but ineffective T-cell response

Answer 13

• staphylococcal enterotoxins and toxic shock syndrome toxins produced by staphylococcus aureus bacteria can induce a massive T cells proliferation and differentiation up to 20% and eventually apoptosis

Question 14

Immune responses can contribute to disease

Answer 14

• some pathologies of infection is directly due to the powerful response of the immune system to the infection
• all pathology is due to the immune system when it comes to kids being infected with the Respiratory Syncytial Virus
• alveoli fuse together and kids can’t breathe properly
• increase of mucous production, increased th2 response, recruitment of damaging eosinophils to the area

Question 15

Bacterial superantigens stimulate a massive but ineffective ______ T cell response

Answer 15

• CD4

Question 16

Inherited immunodeficiency in genes which reveal themselves by enhanced susceptibility to infection or autoimmunity is…

Answer 16

• primary immunodeficiency disease

Question 17

________________ __________________ diseases are sue to environmental factor such as immunosuppressive drugs that adversely impact the immune system

Answer 17

• secondary immunodeficiency

Question 18

Primary Immunodeficiency Diseases

Answer 18

• reveal how the human immune system works

- the mechanisms of immunity and how genes effect the immunity

Question 19

Inherited immunodeficiency diseases are caused by dominant, recessive or x-linked genes defects

Answer 19

• all primary immunodeficiency diseases can be classified as either dominant, recessive or X-linked

Question 20

Dominant Defective

Answer 20

• allele show abnormal properties in kids by interfering with activities of the normal allele

Question 21

Recessive Allele

Answer 21

• function is only elicited when both parents give an abnormal allele to a child

Question 22

X-linked Diseases

Answer 22

• caused by recessive defects in genes on the x-chromosomes
• males will definitely get the abnormal defect
• females will get the defective phenotype only if both X chromosomes are defective

Question 23

Recessive and dominant mutations in the interferon-gamma receptor cause diseases of differing severity

Answer 23

• IFN-gamma is a major cytokine that activates macrophages to produce TNFalpha
• is made by NK cells during innate immunity
• is made by th1 CD4 cells and CD8 T cells during adaptive immunity
• IFN-gamma bind to two receptors called IFNgammaR1 and IFNgammaR2 on monocytes

Question 24

Antibody deficiency leads to an inability to clear extracellular bacteria

Answer 24

• staphylococcus aureus, streptococcus pyogenes, haemophilus influenzae, and streptococcus pneumoniae cannot be recognized by macrophages and neutrophils and thus cleared by antibodies

Question 25

X-linked agammaglobulinemia (XLA)

Answer 25

• defective protein tyrosine kinase that is involved in growth and differentiation of the pre-B cells
• males will lack mature B cells (no antibodies)

Question 26

Diminished production of antibodies also results from inherited defects in ______ cell help

Answer 26

• T
• defects in complement components impair antibody responses and cause the accumulation of immune complexes
• the effector functions by antibodies to clear pathogens and antigens are all facilitated by complement activation

Question 27

Defects in phagocytosis results in enhanced susceptibility to bacterial infection

Answer 27

• phagocytosis by macrophages and neutrophils is the principal method which the immune system removes and destroys bacteria and other microorganisms
• any defect can have profound effect in clearing the infection

Question 28

Defects in T-cell function result in severe combined immune deficiencies (SCIDs)

Answer 28

• whereas B cells contribute only to the antibody response, T cells function in all aspects of adaptive immunity
• T-cell deficient patients will have a broader ranger of susceptibility to infections than those with B-cell defiencies

Question 29

Severe combined immune deficiency (SCID)

Answer 29

• people who make neither T cell dependent antibody response nor cell-mediated immune responses have SCID

Question 30

Transplantation of hematopoietic stem cells

Answer 30

• is used to correct genetic defects of the immune system (bone marrow)
• success of bone marrow transplant is directly correlated with the degree of HLA matching between patient and donor

Question 31

Graft vs. host disease (GVHD)

Answer 31

• when the mature T cells of donor attacks tissue of recipient
• the donor and recipient must share at least one HLA class 1 allotype and one class 2 allotype in order for the reconstitute T cells to respond to antigens presented by the APC

Question 32

Human Immunodeficiency Virus (HIV)

Answer 32

• retrovirus that causes slowly progressing disease
• infects CD4 T cells, macrophages and dendritic cells
• gp120 of HIV tightly binds to CD4 molecules for infection of immune cell

Question 33

Reverse Transcriptase copies the ____ genome into dsDNA that integrates as provirus into the host cell chromosome

Answer 33

• RNA

Question 34

Acquired Immune Deficiency Syndrome (AIDS)

Answer 34

• Seraconversion is when a patient have detectable level of antibodies against HIV in their serum
• initially HIV level in blood drops due to antibodies
• after infection with HIV there is a gradual extinction of CD4 T cells
• T cell count below 200 cells/ul the patient is said to have AIDS

Question 35

HIV infection leads to opportunistic infections

Answer 35

• HIV escapes the immune response and develops resistance to antiviral drugs by rapid mutation