Immunological Tests Flashcards
What specific proteins can be measured in immunological tests and what do they test for?
Tryptase
-increased with mast cell degranulation i.e. in anaphylaxis
Oligoclonal bands (in CSF) -MS
Monoclonal protien
-myeloma
What antibodies can immunological tests look for and what conditions are they associated with?
IgE= antibodies against allergens
IgA= antibodies against tissue transglutaminase (coeliac disease)
IgG AchR abs= MG
What is an anti-nuclear antibody (ANA)?
What are the different patterns you could get with a fluorescent probe and what conditions are these associated with?
Antibodies which target proteins on the nucleus of cells
Homogenous= SLE or drug induced lupus
I.e. used as part of SLE screening test
Nucleolar ANA= systemic sclerosis
Centromeric ANA= CREST syndrome
Cytoplasmic= anti-synthase diseases
What is the potential problem with using ANA for SLE screening?
It has a relatively high FP rate= people testing positive w/o having SLE
ANA are not specific to SLE= they are associated with wide ranger of connective tissue disorders
I.e. results need to be interepreted in the clinical context
What is the purpose of testing extracted nuclear antigens? (ENA)
Can see if autoantibodies in the nucleus are specific to known disease to increase the specificity by looking for specific disease-associated antigens
Ro= SLE/Sjogrens La= SLE/Sjogrens Sm= v specific for SLE RNP= mixed CT disease Scl-70= systemic sclerosis Jo1= polymyositis + dermatomyositis
What immunology investigations can be done if RA was expected?
What is the problem with one of these investigations?
Rheumatoid factor
- IgM autoantibody against IgG
- levels increase with age and other conditions in the absence of rheumatoid arthritis
Anti-CCP
- IgG autoantibody directed against cyclic citrulinated peptide
- very sensitive for RA
What is the pathophysiology behind the anti-TTG antibodies forming in coeliac disease?
What must be done prior to testing for coeliac?
What alternative test can be done for coeliac and when is it indicated?
TTG enzymes join glutamine from gluten onto lysine residues of enzyme under normal conditions
BUT when there is certain genetic background can lead to neo-epitope forming leading to TC and BC autoimmunity against the TTG enzyme
Need to check IgA levels because sufficient levels are required for test to work
IgG endomysial antibodies
-when IgA is too low for anti-TTG test to be done
What test is used for checking for Grave’s disease?
What presentation would indicate this test is appropriate?
TSH receptor IgG with TFT
Presention:
- weight loss
- heat intolerance
- amenorrhea
- diarrhoea
- goitre
- exophthalmus
What immunological tests should be considered as part of acute renal screen?
Myeloma screen= multiple myeloma
- Igs
- serum electrophoresi
- immunofixation
Vasculitis screen= small vessel vasculitis
- ANCA
- MPO
- PR3 antibodies
Anti GBM antibodies= Goodpastures disease
ANA= SLE
C3/C4= SLE or immune complex deposition
What are the different secitons associated with serum electrophoresis?
What does a gamma spike indicate?
Sections seperated based on mass and charged
Albumin Alpha-1 antitrypsin Alpha 2= acid fast glycoproteins Beta-1= Transferin Beta-2= complement + CRP Gamma= Ig
Spike= indicates high level of monoclonal paraprotein productions i.e. very high levels of IgG and also no IgA or IgM
What is the function of immunofixation?
What can the ratio of kappa and lambda chains indicate in multiple myeloma?
Used when paraprotein spike seen on electrophoresis to determine which proteins are responsible for the spike i.e in the context of myeloma
Can indicate whether myeloma is lambda or kappa restricted (based on whether there is a higher ratio of these light chains)
What is the function of flow cytometry?
How can the cell types be determined?
Used for:
- CD4 counts in HIV
- Assess for immunodeficiency
- lymphoproliferative disease
Can determine cell type by size and how granular the cell is
Can label surface proteins with fluorencent marker (i.e. CD3 in TC) to determine cell type
