Acquired Immunodeficiency Flashcards

1
Q

t/f secondary immunodeficiency is more common than primary

A

true

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2
Q

conditions associated with secondary immunodeficiency

A
  • immunosuppressive therapy
  • microbial infection
  • malignancy
  • disorders of biochemical homeostasis
  • autoimmune disease
  • trauma
  • environmental exposure
  • others
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3
Q

excess amounts of infectious agents / their toxins can cause ___

A

active immune system -> nonresponsive state

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4
Q

infection of the bone marrow by viral and bacterial organisms can lead to ___

A

neutropenia or pancytopenia

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5
Q

immunopathogenesis of hiv

A
  • begins with binding of hiv gp120 to cd4 and ccr5 of target cells
  • infected cells migrate to lymph nodes
  • initial replication and infection of nearby cd4 t cells in lymph nodes
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6
Q

acute phase of hiv

A
  • galt is depleted
  • loss of cd4 t cells
  • high viremia and immune activation
  • 1-6 wks after infection
  • nonspecific symptoms
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7
Q

asymptomatic phase of hiv

A
  • clinical latency

- degree of control is determined by levels of cytokines and viral load

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8
Q

symptomatic phase of hiv

A
  • production of anti-hiv cd4 and cd8, and neutralizing anti-hiv antibodies
  • immune response evaded by virus
  • fever, weight loss, diarrhea, lymphadenopathy, infections
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9
Q

aids phase of hiv

A
  • peripheral cd4 t cell <200 cells/ml
  • infections that define aids
  • persistent viremia, progressive disease if not treated
  • death
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10
Q

hallmark of hiv

A

within 1st weeks of infection = massive loss of t cells in the galt and progressive loss of cd4 in peripheral blood

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11
Q

mechanisms of hiv to evade humoral immune system

A
  • neutralizing antibody response becomes ineffective once virus mutates
  • coats itself with sugars (glycan shield) to prevent antibody binding
  • point mutations, insertions, deletions
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12
Q

effect of inflammation on tregs

A
  • tregs: suppress virus-specific cell mediated immune responses
  • loss of th17 = loss of galt
  • loss of galt = translocation of microbial products into peripheral circulation

inflammation = expansion of tregs, less th17

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13
Q

stages of hiv infection

A
  • viral transmission
  • acute hiv infection
  • chronic hiv infection: asymptomatic, aids <200 cd4, advanced hiv <50 cd4
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14
Q

distinguishing features of hiv-2

A
  • same natural history as hiv-1
  • lower levels of plasma virus
  • slower declines in cd4
  • longer asymptomatic period
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15
Q

recommended laboratory hiv testing

A
  • sensitive elisa to detect hiv protein p24

- confirmatory: specific western blot or hiv dna pcr

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16
Q

only other viral agent implicated in significant global immunosuppression

A

measles

- leads to severe and sometimes fatal superinfection

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17
Q

important independent risk factor for severe measles or death from measles

A

malnutrition

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18
Q

most frequent infectious complications of measles

A
  • pneumonia
  • gastroenteritis
  • otitis media
  • gigivostomatitis
  • laryngotracheobronchitis
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19
Q

causes of immune alterations in measles

A
  • direct infection of t cells

- infection of dendritic cells = impaired antigen presenting function and t cell activation

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20
Q

superantigens from bacterial infections bind to ___

A

mhc class II antigens and non-antigen binding region of tcrv = stimulate large numbers of t cells

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21
Q

how do bacterial infections cause secondary immunodeficiency

A
  • many stimulated t cells -> many inflammatory cytokines -> septic shock
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22
Q

effects of mycobacterial lipids

A
  • inhibit dendritic cell devt and production of cytokines
  • macrophages: inhibited tnf-a production
  • myeloid cells: produce cytokines
  • t cells: inhibited responses and secretion
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23
Q

effects of tb

A
  • cd4 lymphopenia
  • lowered cd4/cd8 ratio
  • b cell lymphocytosis
  • cd8 lymphocytosis
  • clinical and radiographic features of more advanced diseases
24
Q

effects of parasite infestation

A
  • diminished vaccine responsiveness
  • susceptibility to infection by other microbes
  • delayed graft rejection
  • higher rate of various malignancies
  • less prone to develop allergy or autoimmune disease
25
possible mechanisms for causing immune dysfunction (parasites)
read!!
26
effects of ebv and cmv
- lower cd4, higher cd8 (inverted cd4/cd8 ratio) - t cells respond poorly to antigens + depressed function - affects b and t cells = broad based transient immune deficiency - cd4/cd8 ratios return to normal in 4-6 wks
27
____ underlies much of predisposition to bacterial and fungal infections in patients with diabetes
neutrophil dysfunction
28
characteristic infections in dm
- disseminated candidiasis - mucormycosis - malignant otitis due to pseudomonas - burkholderia pseudomallei
29
host specific factors that predispose diabetics to infection
- hyperglycemia-related impairment of immune response - vascular insufficiency - sensory peripheral neuropathy - autonomic neuropathy - increased skin and mucosal colonization
30
impaired immune functions in diabetics due to hyperglycemia
- neutrophil chemotaxis and adherence to vascular endothelium - phagocytosis - intracellular bactericidal activity - opsonization - cell mediated immunity
31
major pathway for glycemic damage in diabetics
methylglyoxal glycation
32
effects of vascular insufficiency in diabetics
- local tissue ischemia - impaired local inflammatory response - impaired absorption of antibiotics
33
effect of autonomic neuropathy in diabetics
urinary retention and stasis = uti
34
organism-specific factors that predispose diabetics to infection
- glucose inducible proteins promote adhesion of candida | - ketone reductases let rhizopus thrive (mucormycosis)
35
effects of hemodialysis
- reduced t cell function - diminished antibody production - compromised neutrophil and dendritic function - low expression and/or function of igg fc receptors
36
examples of immune hyporesponsiveness
- esrd = high levels of il2 receptor = diminished response to il2 - uremic pts = suppress mitogenic response of t cells - chronic peritoneal dialysis = bacterial peritonitis*
37
possible mechanisms of immunodeficiency in malnutrition
- low adipocytes = low leptin - low leptin = reduced t cell response - weakened barrier mucosa, intestinal malabsorption - micronutrient deficiencies
38
effects of malnutrition on immune function
- decreased lymphocyte numbers - absent dth - decreased phagocytic activity - low serum antibody levels - increased infections
39
dramatic feature of protein-energy malnutrition
lymphoid atrophy
40
immune defects in protein-energy malnutrition
read
41
t/f antibodies in malnutrition are elevated, but they have impaired quality and affinity
true
42
hematopoietic tumors
read
43
examples of bacteria that asplenic patients can get
encapsulated bacteria - s penumoniae - n meningitidis - h influenzae
44
immunizations for patients on elective splenectomy
anti-pneumococcal, anti-hemophilus influenzae, anti-meningococcal at least 2 wks before surgery
45
defects i the complement system in sle
read
46
most common quantitative disorder in sle
t cell lymphopenia
47
disorders of protein loss
read
48
inflammatory response in trauma
- loss of epithelial barriers - vasodilation and increased vascular permeability - cellular activation and increased adhesion toe dnothelia - neuroendocrine stress response
49
mechanism of inflammatory response in trauma
systemic inflammatory response syndrome | - activation of monocytes and macrophages (il1, tnf)
50
effects of burns
- depressed cd4 % - reduced t cell helper activity (reduced il2) - depressed neutrophil function
51
causes of immunodeficiency in newborns
- secondary lymph organs not mature - no memory cells - innate immunity*
52
causes of immunodeficiency in aging
- decreased ability to clear infections - decline in hematopoietic tissue in marrow - defects in dna
53
t/f depressed cellular immunity during pregnancy is assumed to have a survival benefit
true
54
effects of stress
- increased rates of rti - reactivation of herpes virus - increased cancer - reduced nk cell activity - depressed lymphocyte mitogen responses
55
other environmental conditions that can cause immunosuppression
- confinement, isolation, sleep-cycle alterations - acute sleep deprivation - prolonged bedrest - chronic hypoxia
56
adverse consequence of medical intervention
read