Immunology Flashcards
How do you diagnose an allergy in the lab?
IgE serology
Allergen Specific IgE ( immunocap assays )
What are the immunocap allergen mixes?
① aero allergen mix (7 )
• cockroach
• dust mite
• Grass
• dog
• cat
• aspergillas tumigata
• alternaria alternata
② food mix (6)
• peanuts
• cowmilk
• soy bean
• wheat
• egg white
• fish
How do you differentiate a true peanut allergy?
Presence of Ara h 1, 2, and 3 specific IgE
Define immunodeficiency
Immunodeficiency is the result of a diverse group of abnormalities of the immune system resulting primarily in an increased incidence of infection.
What are the 10 warning signs of primary immunodeficiency? NB
1) positive family history
2) 2 or more months on antibiotics with little effect
3) 8+ new ear infections in one year
4) 2+ serious sinus infections in 1 year
5) 2+ pneumonias in 1 year
6) failure to gain weight/grow normally
7) recurrent deep skin/organ abscesses
8) 2+ deep seated infections
9) persistent thrush in mouth or other after age 1
10) need for IV antibiotics to resolve infections
How do you screen for PID (primary immunodeficiency disease)
History: SPUR
S erious infections needing AB
P ersistant infections
U nusual organisms
R eccurent infections
Lab tests
1) FBC and diff
2) total serum immunoglobulins (Ig G,A, E, M) and IgE subclasses
3) Total haemolytic complement (C3+C4)
4) Flowcyto analysis of Tcells, B-cells, NK cells
What are limitations of serological procedures?
1) Antibodies not always produced
2) high pre-existing antibody levels
3) many antigenic subtypes for some pathogens
When do we use serodiagnosis
1) HIV
2) rickettsia (tick bite)
3) syphillis
4) Chlamydia
5) toxoplasmosis
How do you tell the difference between acute and chronic disease by serology?
Chronic has IgG 4 fold above the basal. Increased titres must be shown in follow up tests 4-6 weeks later.
What antibody is the mainstay of chlamydia infection?
IgA
What serological procedures do we use to detect antibodies?
1) Indirect immunofluorescence - add anti human antibody and look under microscope
2) enzyme linked immunoassay- anti human antibody added = colour change if antigen present (measured by spectrophotometer)
Tick bite fever - how do you use serology to tell if it’s acute or chronic?
Phase 2 titres > Phase 1 titres = acute
Phase 1 titres > phase 2 titres = chronic
What is central tolerance?
Tolerance mechanisms that operate in the thymus before the maturation and circulation of T cells
Requirements for a autoimmune disease?
Genetic factor + infection/environmental exposure = immune regulation →autoimmunity
What is the incidence of autoimmune diseases?
8% of the population, 78% of which are female
What type of hypersensitivity reactions cause tissue damage in autoimmune diseases?
II, III, IV
Causes of autoimmunity
Age
Failure of self tolerance
Exposure to “privilege” sites
HLA allele associated with ankylosing spondylitis
B27 (87%)
HLA allele associated with Goodpasture syndrome
DR2 (16%)
HLA allele associated with rheumatoid arthritis
DR4 (4%)
HLA allele associated with insulin dependent DM
DR3/DR4 (3%)
Autoimmune diseases with well defined auto antigen
Graves
Hashimoto
T1 DM
Pernicious anaemia
Myasthenia gravis
Autoimmune diseases with poorly defined auto-antigen
Multiple sclerosis
SLE
Rheumatoid arthritis
What antigen is diagnostic of SLE?
dsDNA, SMdp
What antigen is diagnostic of CREST syndrome?
Centromere P
CENP
Serodiagnosis of Rheumatoid arthritis
Rheumatoid factor
Anti-CCP antibodies
Risk factors for antiphospholipid syndrome
Hyperlipidaemia
Ypertension
Cigarette smoking
Pre-exciting inflam disorder
Serodiagnosis of anti-phospholipid syndrome
Anti-cardiolipin antibodies (ACLA):
ACLA IgM and IgG
ACLA IgA
Antibodies to beta 2 glycoprotein-1
Antibodies in myasthenia gravis
SOX1
AchR
Autoantibodies in polyneuropathies
Gangliosides (GM, GD, GQ’s)
Pathogenesis of rheumatoid arthritis
Recognition of auto-antigen by auto reactive CD4 T lymphocytes
Activation of autoreactive B lymphocytes
Formation of auto-antibodies
Inflam synovitis and tissue damage mediated by phagocytes, antibodies and complement
Antigen specific ANA’s in SLE
Anti-dsDNA
Anti-Sm
Anti-histone (drug induced lupus)
