There is a long list of tests an immunologist does to aid the clinician in making a diagnosis. Most tests are performed on blood but other samples such as cerebrospinal fluid (CSF) or urine are also tested. This article summarizes the main tests performed by hospital immunology laboratories.
Immunodeficiency Tests
There are many components that are essential for a healthy immune system. Immunodeficiency can be caused by a number of factors and is a frequent health problem. Common tests done to investigate this are:
- Lymphocyte proliferation
- Neutrophil/lymphocyte function
- Cytokine measurement
- HIV monitoring: CD3,CD4,CD8
Allergy Tests
Hypersensitivity (allergic) reactions are immune responses to environmental antigens such as pollen and food and have a relatively high incidence. Reactions to specific allergens can be tested, as well as general measures of allergy.
Specific allergy tests:
- cat/grass/house dust mites
- Milk/wheat/Egg
- Mixed allergens e.g. nuts, tree pollen.
General measures of allergy:
- Total IgE
- Mast cell tryptase
Neuroimmunology Tests
Neuroimmunology tests are used to investigate conditions that involve interaction between the nervous system and immune system such as arthritis and multiple sclerosis. Neuroimmunology tests include:
- Oligoclonal IgG bands
- Spectrophotometric scan
- Tau protein
- Caeruloplasmin
- Acetylcholine receptor
Precipitin Assays
The precipitin test was the first quantitative method developed for measuring antibody levels in the blood. It is only rarely used these days, for instance when investigating the following infections:
- Aspergillus fumigatus
- Candida Albicans
- Mycopolyspora faeni
Complement Assays
The complement system is an essential part of the immune system, being involved in anti-bacterial responses. The complement system is composed of a large number of serum proteins. The list of tests an immunologist does to assess function of these serum proteins include:
C1q, C1r, C1s, C2, C3/C4, C3d, C5, C6, C7, C8, C9, Factor-B, Factor-D, Factor H and Factor I.
Antibody Deficiencies
General investigation into the levels of the different classes and subclasses of immunoglobulin (antibody) can be performed:
- IgG, IgA, IgM
- IgG subclasses (IgG1,2,3,4)
- IgA subclasses (IgA1,2)
Tests for specific functional antibodies can also be carried out, such as:
- Tetanus toxoid
- Influenza B
- Pneumococcus
Tests for Vasculitis
Vasculitis (inflammation of the blood vessels) can be investigated by the following tests:
- Neutrophil cytoplasmic antibodies
- Von Willebrand factor
- CRP
- ANA
- ANCA
Malignant Disease
Leukemic cells present in the blood can be examined in the laboratory for the presence of certain surface molecules. This can determine the type of leukemia.
- Myeloid Leukemia
- B-ALL (B cell acute lymphocytic leukemia)
- T-ALL (T cell acute lymphocytic leukemia)
This type of testing can also be used to diagnose lymphoproliferative disease such as:
- T-NHL (non-Hodgkins lymphoma)
- Hairy cell leukemia
- Hodgkins lymphoma
- Myeloma
Autoantibodies
The immune system protects us against invading pathogenic organisms such as bacteria, viruses and fungi. Unfortunately unwanted immune reactions against our own tissues can occur and cause disease. One method to investigate this is by the detection of autoantibodies. The list of tests an immunologist does to assess autoantibody production include:
- Adrenal antibodies
- Cardolipin antibodies
- Centromere antibodies
- Epidermal antibodies
- Gastric parietal cell antibodies
- Glomerular basement membrane antibodies
- Intrinsic factor antibodies
- Islet cell antibodies
- Myocardial antibodies
- Skeletal muscle antibodies
- Thyroid antibodies
- Rheumatoid Factor
References
University of Birmingham Clinical Immunology Service website: https://www.uhb.nhs.uk/pdf/LaboratoryHandbookUob.pdf
Immunobiology (Seventh Edition), K.Murphy, P.Travers, M.Walport, 2008, published by Garland Science.
