Immu 11: Case studies in Immunology Flashcards
what happens in anaphylaxis
- type I hypersensitivity reaction
- cross-linking of IgE on mast cells
- leads to mast cell degranulation
- results in:
- increased vascular permeability
- smooth muscle contraction
- inflammation and increased mucus production
What type of reaction is anaphylaxis?
Type 1 hypersensitivity - cross-linking of IgE on the surface of mast cells, causing mast cells to degranulate and release histamines and leukotrienes
what is the most common presentation of anaphylaxis
- urticaria/ angioedema
- followed by upper airway oedema
what are the types of latex allergy (2)
- type 1 hypersensitivity to latex can gross react with foods eg avocado/banana (latex fruit syndrome)
- type 4 hypersensitivity - contact dermatitis, 24-48hrs after exposure
3 methods of investigating latex allergy
- in vitro tests for specific IgE to latex
- in vivo skin prick testing
- in vivo patch testing
what disorders are associated with recurring meningococcal meningitis infections (3)
- complement deficiency - increased risk of infection by encapsulated organisms
- antibody deficiency - recurrent bacterial infections - URTI/LRTI
- neurological - disturbance of BBB
what history of infections suggests immune disorders (mnemonic)
SPUR
- Serious
- Persistant
- Unusual
- Recurrent
Def in complement can result in what serious infectious condition?
What test would you do?
What results would you expect?
Meningicoccal sepsis
Test: AP50 (alterantive pathway) and CP50 (classical pathway)
Both AP50 and CP50 abnormal, suggesting that there must be something wrong with the final common pathway (as this is the only thing both tests share) - specifically, in meningicoccal septicaemia, it is C7 affected usually
How can we test the function of complement (2)
CH50 - functional test of the integrity of the classical complement cascade
AP50 - functional test of the integrity of the alternative complement cascade
how do you manage a patient with a complement deficiency
- Vaccines (increase R of encapsulated bacterial infections):
- meningovax
- penumocax
- HIB vaccine
- daily prophylactic penicillin
- high level of suspicion
what illness can you get after taking penicillin for an infection
serum sickness
- penicillin can bind to cell surface proteins
- acts as a neo-antigen which stimulates a very strong IgG response
- the individual is therefore sensitised to penicillin
- subsequent exposure to penicillin leads to - formation of immune complexes with circulating penicillin
- production of more IgG antibodies
- causes: renal dysfunction, arthralgia, purpura
what are the investigations for serum sickness (3)
- low serum C3 + C4
- specific IgG to penicillin
- characteristic biopsy features (skin and kidneys) - infiltration of macrophages and neutrophils, deposition of IgG, IgM and complement
Presentation of serum sickness
Immune complexes deposit into small vessels
- Glomerulonephritis: deposition in glomeruli (get loss of renal function - high creatinine, proteinuria, haematuria)
- arthralgia and a vasculitis rash
- disorientation: vasculitis affecting cerebral vessels may compromise oxygen supply to the brain
- purpura: blood vessels are likely to leak, so get local haemorrhage
how do you manage serum sickness
- discontinue penicillin immediately
- decrease systemic inflammation via corticosteroids
- ensure appropriate fluid balance
list 3 reasons for chronic infections in a 3 year old
- cystic fibrosis
- local factors eg foreign body
- ciliary disorders
features of X linked agammaglobulinaemia
- failure of pre-B cells to mature in the bone marrow (so get low B cells - so can’t produce immunoglobulins)
- leads to failure to produce immunoglobulin
how is X linked agammaglobulinaemia managed
immunoglobulin replacement therapy
- pooled serum Ig
- every 3 weeks
- indefinite
features of Multiple Myeloma (7)
- unusual or vertebral fractures (lytic lesions)
- high ESR
- high calcium
- measure Ig/ electrophoretic strip
- urinary Bence Jone proteins
- anaemia (since malignant clone of plasma cells crowds out the normal RBC)
- more susceptible to infections (since suppression of normal immunoglobulin by the malignant clone results in a functional antibody deficiency)
- Rouleaux formation on blood film of RBCs
features of rheumatoid arthritis (4)
- peripheral, symmetrical polyarthritis + stiffness
- persists for >6w
- may be associated with RF +/ anti-CCP antibodies
- post-partum presentation common
what is rheumatoid factor
- antibody against Fc region of human IgG
- assays look for IgM RF usually
- also look at anti-CCP antibodies (highly specific)
list genetic predispositions to rheumatoid arthritis (3)
HLA DR - DR4, DR1
PADI type 2 and 4
PTPN 22
how is rheumatoid arthritis managed
1st line
- methotrexate (Disease Modifying Drugs)
- sulphasalazine/ hydroxychloroquine/leflunomide
further
- anti TNF alpha
- rituximab - anti CD20
- abatacept - binds CD80 and CD86
- tocilizumab - against IL6 receptor
- Pt has malar rash + tender joints + HTN + oedema. You then see the attached image. What is going on?
- What effect does this have on complement pathway?
- What would renal biopsy show?
- SLE: pic shows dsDNA
- Low C3 and C4: complement gets consumed since immune complexes bind to C1q and activate the classical pathway
- Diffuse proliferative nephritis
Rouleaux formation in which blood condition?
Multiple myeloma
