Infections pt. 2 Flashcards
A CD4+ count (Helper T cells) of what value allows for diagnosis of AIDS:
What is normal value?
<200/mm3
800-1000/mm3
What is the window period for HIV?
Time between infecction and presence of anitbodies;
4-7 weeks after blood transfusion
6-14 months after sexual activity
Clinical manifestations of AIDS includes:
- Opportunistic infections/cancer
- Serologically positive antibodies
- Low CD4+ counts
What are these types of hypersensitivites:
- Hypersensitivity to environmental (exogenous) antigens
- Disturbance in immunological tolerance to self-antigens
- Allergy
- Autoimmunity
What are these types of hypersensitivites:
- Reaction to tissues of another individual
*
- Alloimmunity Immune
Difference in Immediate hypersensitivity reactions
vs.
Delayed hypersensitivity reactions
Immediate
- Caused by anaphylaxis
- More rapid and severe
Delayed
- Caused by cells (T-cells/macrophages)
- Takes several hours
What are Type I Hypersensitivites caused by:
How does it work:
Environmental antigens (allergies)
IgE bind to Fc receptor of mast cell and cause release of histamine
What are common manifestations of type I hypersensitivites?
- Urticaria (hives)
- Atopic dermatitis (eczema)
- Asthma
What occurs during type II hypersensitivities?
- Antigen biinds to specific tissues/cells
- Complement/antibodies/neutrophils:
- Destroy the cells
- Causes cell malfunction
An example of type II hypersensitivites is:
Grave’s disease
What occurs during type III hypersensitivites?
- Antigen-antibody complexes form in circulation
- Deposit on vessel walls/tissue
- Lysosomal enzymes cause tissue damage
What are some examples of type III hypersensitivities?
- Serum sickness
- Raynaud disease
What are type IV hypersensitivities?
Cell-mediated hypersensitivity that does not involve antibodies:
T-helper cells direct killing by cytotoxic T cells or phagocytic cells
What are examples of type IV hypersensitivities?
- Poison ivy/metal reaction
- TB skin test
What are these terms:
- State of immunological immunity so individual does not attack own cells?
A failure in ^ process results in:
- Tolerance
Tolerance breakdown= autoimmunity
