Alterations of immune function including HIV Flashcards
(113 cards)
1
Q
A
2
Q
What is immunity?
A
A complex interrelated series of events that provides constant protection for the body.
3
Q
Can a person experience infection even with a normally functioning immune system?
A
Yes, if exposed to a sufficient load of a pathogenic microorganism or a particularly virulent strain.
4
Q
What can inappropriate immune responses lead to?
A
Serious or life-threatening conditions.
5
Q
What are the four types of inappropriate immune responses?
A
- Exaggerated against environmental antigens (allergy)
- Directed against transplanted foreign tissues
- Misdirected against the body’s own cells (autoimmune diseases)
- Insufficient to protect the host (immune deficiency diseases)
6
Q
What is hypersensitivity?
A
An immune response that is exaggerated or activated inappropriately, resulting in disease or damage.
7
Q
How many types of hypersensitivity reactions are there?
A
Four.
8
Q
What are the four types of hypersensitivity reactions?
A
- Type I: immunoglobulin E-mediated reactions
- Type II: tissue-specific reactions
- Type III: immune complex–mediated reactions
- Type IV: cell-mediated reactions.
9
Q
What is autoimmunity?
A
When the immune system attacks the body’s own cells due to a failure to recognize self-antigens.
10
Q
What is required for hypersensitivity reactions to occur?
A
Sensitization against a particular antigen, leading to a primary immune response.
11
Q
What are immediate hypersensitivity reactions?
A
Reactions that occur within minutes to a few hours after exposure to an antigen.
12
Q
What are delayed hypersensitivity reactions?
A
Reactions that may take several hours to appear and reach maximum severity days after re-exposure to the antigen.
13
Q
What are allergens?
A
Environmental antigens that cause hypersensitivity.
14
Q
What is the estimated percentage of the population in Australia and New Zealand with at least one allergy?
A
Approximately 20%.
15
Q
What is the predicted population suffering from allergic diseases in Australia by 2050?
A
7.7 million (26.1% of the population).
16
Q
What type of hypersensitivity reactions are the most common?
A
Type I hypersensitivity reactions.
17
Q
What mediates Type I hypersensitivity reactions?
A
Antigen-specific immunoglobulin E (IgE) and products of tissue mast cells.
18
Q
What occurs during the first exposure to an allergen in Type I hypersensitivity?
A
An allergen is phagocytosed by an antigen-presenting cell, stimulating B cells to produce IgE.
19
Q
What happens during the second exposure to the allergen in Type I hypersensitivity?
A
The allergen cross-links to surface-bound IgE on mast cells, causing the release of histamine.
20
Q
What are the clinical manifestations of Type I reactions primarily attributed to?
A
The biological effects of histamine.
21
Q
What are common symptoms of gastrointestinal allergy?
A
- Vomiting
- Diarrhoea
- Abdominal pain.
22
Q
What is urticaria?
A
A dermal manifestation of allergic reactions characterized by white fluid-filled blisters and redness.
23
Q
What can cause rhinitis and conjunctivitis in allergic reactions?
A
Allergens affecting the mucous membranes of the nose and eyelids.
24
Q
What is atopy?
A
A genetic predisposition to develop allergies.
25
What is the most rapid and severe immediate hypersensitivity reaction?
Anaphylaxis.
26
What are the consequences of anaphylaxis?
* Severe bronchoconstriction
* Oedema of the throat
* Breathing difficulties
* Decreased blood pressure.
27
What is required for individuals with severe systemic anaphylaxis?
To avoid exposure to specific allergens and carry an auto-injector (e.g., Anapen® or Epi Pen®).
28
What does adrenaline do during anaphylaxis?
Promotes bronchodilation and vasoconstriction to alleviate symptoms.
29
What is the incidence of food allergies in infants in Australia and New Zealand?
Approximately 10%.
30
What is the role of antihistamines in allergic reactions?
To alleviate symptoms of allergies.
31
What is the mechanism of Type I IgE-mediated hypersensitivity reactions?
IgE binds to mast cells, leading to degranulation and histamine release upon allergen re-exposure.
32
What is the role of adrenaline in anaphylaxis?
Adrenaline promotes sympathetic nervous system function, which promotes bronchodilation and causes vasoconstriction, increasing blood pressure and perfusion to vital organs.
## Footnote
It temporarily alleviates the effects of anaphylaxis and individuals are taught to self-inject with an adrenaline pen.
33
Define Type II hypersensitivity reactions.
Type II hypersensitivities are reactions against a specific cell or tissue, involving antibodies binding to tissue-specific antigens.
## Footnote
Symptoms depend on which tissue expresses the antigen.
34
What are the four mechanisms by which Type II hypersensitivity reactions can affect cells?
The mechanisms include:
* Destruction of target cells by antibodies activating the complement system
* Phagocytosis of antibody-antigen complexes by macrophages
* Natural killer cells destroying target cells
* Alteration of cell function by antibodies binding to receptors.
35
What is immune thrombocytopaenia purpura?
It is a condition where antibodies against platelets cause their removal in the spleen, leading to decreased platelets and easy bruising, termed purpura.
## Footnote
It is an example of a Type II hypersensitivity reaction.
36
Describe the mechanism of Type III hypersensitivity reactions.
Type III reactions involve immune complexes formed in circulation that deposit in tissues, activating the complement system and attracting neutrophils that release enzymes causing tissue damage.
## Footnote
It differs from Type II as the antibody binds to soluble antigens rather than those on cell surfaces.
37
What are the clinical examples of Type IV hypersensitivity reactions?
Examples include:
* Graft rejection
* Skin test for tuberculosis (Mantoux test)
* Allergic contact dermatitis from substances like nickel and latex.
38
What characterizes hyperacute rejection in transplantation?
Hyperacute rejection is immediate and occurs due to pre-existing antibodies to antigens on the vascular endothelial cells in the grafted tissue.
## Footnote
It is also known as a white graft.
39
What is the ABO blood group system?
The ABO blood group consists of two major carbohydrate antigens, A and B, which can result in four blood types: type A, type B, type AB, or type O.
## Footnote
The blood types are determined by the presence or absence of these antigens on red blood cells.
40
What antibodies are present in individuals with blood group A?
Individuals with blood group A have IgM antibodies against the B antigen.
## Footnote
Their red blood cells express the A antigen.
41
What is the significance of matching MHC molecules in organ transplantation?
Close matching of MHC molecules reduces the recipient's immune system's capacity to attack the transplanted organ, minimizing rejection.
## Footnote
MHC molecules are also known as human leucocyte antigens (HLA).
42
What is chronic rejection in transplantation?
Chronic rejection occurs after months or years of normal function and is characterized by slow, progressive organ failure.
## Footnote
It may result from a weak cell-mediated reaction against minor histocompatibility antigens.
43
What are the symptoms of latex allergy in healthcare workers?
Symptoms include erythema, itch, and swelling typical of IgE-mediated allergy clinical manifestations.
## Footnote
Type IV reactions related to contact dermatitis are also common.
44
What is the primary treatment recommendation for latex allergy?
The best treatment is the avoidance of latex gloves and the use of non-latex powdered gloves.
## Footnote
This recommendation aims to decrease the risk of developing a latex allergy.
45
How do T cytotoxic cells contribute to Type IV hypersensitivity?
T cytotoxic cells attack and destroy cellular targets directly in Type IV hypersensitivity reactions.
## Footnote
Helper T cells produce cytokines that recruit phagocytes, especially macrophages.
46
What is the relationship between ABO antigens and antibodies?
Individuals develop antibodies against the ABO antigens they do not possess, leading to immune reactions in incompatible blood transfusions.
## Footnote
For example, type A individuals will have antibodies against B antigens.
47
What antigens and antibodies are associated with blood type A?
Antigens: A
Antibodies: Anti-B
48
What antigens and antibodies are associated with blood type B?
Antigens: B
Antibodies: Anti-A
49
What antigens and antibodies are associated with blood type AB?
Antigens: A and B
Antibodies: None
50
What antigens and antibodies are associated with blood type O?
Antigens: None
Antibodies: Anti-A and Anti-B
51
What are naturally occurring antibodies?
Antibodies acquired through exposure to environmental antigens that are similar to self-antigens
52
Why can a type A individual not receive type B blood?
Because they possess anti-B antibodies that will react with type B antigens
53
What is the consequence of transfusing incompatible blood?
Severe transfusion reactions, including agglutination and complement-mediated lysis
54
Which blood type is considered the universal donor?
O negative
55
Which blood type can receive from all blood types?
AB positive
56
What is the primary antigen of the Rhesus (Rh) blood group system?
D antigen
57
What does it mean to be Rh-positive?
To express the D antigen on red blood cells
58
What is the risk associated with Rh-negative individuals receiving Rh-positive blood?
They may produce anti-D antibodies leading to haemolytic reactions
59
What is self-tolerance in the immune system?
The ability to not react against one's own antigens
60
What is autoimmunity?
A disturbance in the immunological tolerance of self-antigens
61
What are autoantibodies?
Antibodies produced against self-antigens
62
What autoimmune disease is characterized by the destruction of thyroid cells?
Hashimoto hypothyroidism
63
What autoimmune disease is associated with the destruction of insulin-producing cells?
Type 1 diabetes
64
What is systemic lupus erythematosus (SLE)?
A serious autoimmune disorder characterized by the production of various autoantibodies
65
What is the characteristic rash associated with SLE?
Butterfly rash on the face
66
What is the significance of IgG anti-D antibodies in pregnancy?
They can cause haemolytic disease of the newborn if a Rh-negative mother is exposed to Rh-positive fetal blood
67
What is the main cause of acute rheumatic fever?
Antibodies induced by group A streptococcal infection that cross-react with heart antigens
68
What is a common clinical finding for diagnosing SLE?
Presence of at least 4 out of 11 criteria
69
Fill in the blank: Type O individuals cannot accept blood from any of the other three types due to having both _______ and _______ antibodies.
Anti-A, Anti-B
70
True or False: Blood type AB can donate to all blood types.
False
71
What is the minimum number of criteria needed to indicate that an individual has SLE?
At least 4 of the 11 criteria.
72
What is a characteristic feature of the facial rash associated with SLE?
Malar rash in a butterfly shape.
73
List three types of rashes associated with SLE.
* Facial rash (malar rash)
* Discoid rash
* Photosensitivity rash.
74
What are the symptoms of serositis in SLE?
Inflammation of membranes of the lung (pleurisy) or heart (pericarditis).
75
What are the treatment goals for SLE?
Control symptoms and prevent further damage by suppressing the autoimmune response.
76
Name two types of drugs used to treat severe symptoms of SLE.
* Corticosteroids
* Immunosuppressive drugs.
77
True or False: There is a cure for SLE.
False.
78
What role do sex hormones play in autoimmune diseases, particularly in women?
They affect the immune system and susceptibility to autoimmune disorders.
79
What is the term for when an individual has an insufficient immune response?
Immunocompromised.
80
Differentiate between primary and secondary immune deficiencies.
Primary are congenital due to genetic defects; secondary are acquired due to other conditions.
81
What is the clinical hallmark of immune deficiency?
A tendency to develop unusual or recurrent severe infections.
82
List the five groups of primary immune deficiencies.
* B cell deficiencies
* T cell deficiencies
* Combined immune deficiencies
* Complement deficiencies
* Phagocyte deficiencies.
83
What is Severe Combined Immunodeficiencies (SCID)?
Lack of both T and B cells, little or no antibody production or cellular immunity.
84
Fill in the blank: Conditions associated with secondary immune deficiencies include _______.
Pregnancy, ageing, malignancies, infections.
85
What is the most destructive secondary immunodeficiency?
Acquired immunodeficiency syndrome (AIDS).
86
How does HIV suppress the immune response?
By infecting and destroying helper T cells.
87
What percentage of people with HIV know their status?
54%.
88
List two routes of HIV transmission.
* Blood or blood products
* Sexual transmission.
89
What is the role of reverse transcriptase in HIV?
Converts RNA into double-stranded DNA.
90
True or False: HIV can remain latent in infected cells.
True.
91
What is the structure of the HIV virion?
Core of two identical strands of viral RNA coated in a protein structure with viral proteins gp41 and gp120.
92
What is the core structure of the HIV virion?
Two identical strands of viral RNA coated in a protein structure with viral proteins gp41 and gp120 on its surface.
93
How does HIV infection begin?
When a virion binds to CD4 and chemokine receptors on a susceptible cell.
94
What is the primary surface receptor on HIV?
The envelope protein gp120.
95
What is the typical range of CD4+ cells in individuals who are not HIV-infected?
600–1200 CD4+ cells per cubic millimetre of blood.
96
What happens to CD4+ cell counts as HIV disease progresses?
The CD4+ count generally declines.
97
What are the clinical manifestations of CD4+ cell depletion?
Severely diminished response to infectious pathogens and malignant tumours.
98
What is the window period in HIV infection?
The period between infection and the appearance of antibody.
99
What symptoms might individuals experience in the early stages of HIV disease?
Mild symptoms resembling influenza, such as night sweats, swollen lymph glands, diarrhoea or fatigue.
100
What is the average time from HIV infection to the development of AIDS?
Just over 10 years.
101
What percentage of untreated HIV-infected individuals will eventually progress to AIDS?
Approximately 99%.
102
What are some neurological complications associated with AIDS?
HIV-associated cognitive dysfunction, which may affect adults or children.
103
What is the most common neurological disorder in individuals with AIDS?
HIV-associated cognitive dysfunction (HIV encephalopathy).
104
What are some cardiac complications that individuals with HIV and AIDS may face?
Dilated cardiomyopathy, myocarditis, pericardial effusion, endocarditis, pulmonary hypertension.
105
What is the current regimen for the treatment of HIV infection?
Highly active antiretroviral therapy (HAART).
106
What types of inhibitors are included in HAART?
Reverse transcriptase inhibitors, integrase inhibitors, protease inhibitors.
107
What is PrEP?
Pre-exposure prophylaxis, effective in reducing the risk of HIV infection in high-risk adults.
108
What medications are commonly used as PrEP?
Tenofovir and emtricitabine.
109
Why is developing an HIV vaccine challenging?
HIV is genetically and antigenically variable, and circulating antibodies in AIDS patients do not appear to be protective.
110
Fill in the blank: The presence of circulating antibody against HIV indicates infection by the _______.
[replicating virus]
111
True or False: Individuals with HIV can be seronegative for several months after infection.
True
112
What are AIDS-defining opportunistic infections?
Infections that occur in individuals with significantly weakened immune systems due to HIV.
113
List some examples of opportunistic infections associated with AIDS.
* Cryptosporidiosis
* Pneumocystosis
* Toxoplasmosis
* Candidiasis
* Cryptococcosis
* Mycobacteriosis
* Cytomegalovirus infections
* Herpes simplex virus infections
