Immunology Flashcards
1
Q
Desensitisation
A
- Only attempt when there are no other options
- High risk procedure (Informed consent)
- Only temporary tolerance, the hypersensitivity returns
- The exact mechanism is poorly understood
- IgE mediated reactions respond better
- Severe skin reactions such as Stevens Johnson and Toxic Epidermal Necrolysis are absolute contraindications
2
Q
Desensitisation Procedure
A
The general process includes:
- Location – constant observation, resuscitation equipment available
- Premedication – usually an antihistamine and steroid dose
- Extremely slow infusion – start with 1/10,000 dose and work up by doubling the dose every 15 minutes
3
Q
Antigen presentation
A
- Major site for interaction between antigen presenting cells and T Cells is lymph node
- They do this by chemotaxis.
- During the migration, DCs undergo a process of maturation and develop an increased ability to communicate with T cells.
- Enzymes within the cell digest the swallowed pathogen into smaller pieces containing epitopes, which are then presented to T cells using MHC.
4
Q
Antigen-specific immune response that eradicates viruses
A
- Cytotoxic T cells destroy virally infected cells and tumor cells, and has been implicated in transplant rejection.
– Also known as CD8+ T cells
– Recognize their targets by binding to antigen associated with MHC Class I.
5
Q
C3 Complement deficiency
A
C3 deficiency is associated with recurrent bacterial infections,
6
Q
MAC, C5-C9 deficiency
A
Associated with infection by Neisseria species (especially the meningococcus)
7
Q
Complement deficiencies
A
- Rare
- Predispose to bacterial infections
- Predispose to SLE (most common autoimmune disorder associated with complement deficiencies
8
Q
C1 Deficiency
A
- Most commonly C1q
- 90% have SLE with clinical features
- commonly recurrent bacterial infections
- C1r and C1s - development of SLE particularly with renal complications (very rare
9
Q
Highest risk of HIV transmission
A
Receptive anal intercourse
10
Q
HIV entry to host cell
A
- Attachment by GP120 to CD4 antigen receptor
- Co-receptor CXCR4 (T cells), CCR5 (Macrophages)
- Post attachment viral envelope and host cell membrane fuses
- RNA released into cell
- Reverse transcriptase makes a DNA copy of the RNA genome then a second copy of the DNA is made. These then join covalently
5.
- R5 Strain: uses CCR5 for CD4 cell entry (less aggressive)
- X4 strain: uses CXCR4 for CD4 cell entry (more aggressive)
11
Q
HIV R5 Strain
A
– most frequently transmitted
– less aggressive
– infects macrophages and T cells
– use CXCR5 for CD4 cell entry
12
Q
HIV X4 strain
A
– infects only T cells and T cell lines
– more aggressive
– use CXCR4 for CD4 cell entry
13
Q
HIV-2
A
– less virulent – lower viral load – lower rates of vertical transmission – slower progression – HIV-2 is less virulent. – Seen mainly in western central Africa and southern and western India.
14
Q
HIV-1
A
is the most common type in western world
15
Q
HIV-1
A
- Most common type in western world
- Painful mucocutaneous ulceration is one of the most distinctive manifestations of acute HIV infection. - - Shallow, sharply demarcated ulcers with white bases surrounded by a thin area of erythema may be found on the oral mucosa, anus, penis, or esophagus. These ulcerative lesions may reflect mucocutaneous disease associated with acute HIV infection or coincident sexually transmitted infections, such as herpes simplex virus, syphilis, or chancroid.
