In this section
This section deals with clinical conditions associated with infection and immunity which are covered by the Immunology department. For each clinical condition, the relevant immunological tests are listed together with a short explanation of their use.
Please phone Immunology Clinical Staff (ext 66468) to discuss the investigation of recurrent unusual infections.
Primary immunodeficiency (PID) can cause preventable death or morbidity. Consider PID in patients with:
- recurrent infection
- severe infection
- infection refractory to antibiotics
- unusual infection
Don’t forget that PID can present in childhood and adulthood as well as in infancy.
Guidelines for testing are available from the UK Primary Immunodeficiency Network (UKPIN)
Patient information is available from the Primary Immunodeficiency Association
Primary immunodeficiency
The following panels of tests are available for investigating patients:
- Immunoglobulin levels: Immunoglobulins (IgG, IgA, IgM), IgG subclasses
- Antibody responses: Functional antibodies Hib/Pneumococcus
- Complement activity: CH50 activity, Complement C3, Complement C4
- Skin tests – by arrangement
- Immunodeficiency (T&B Lymphocyte Subsets) – Tel: 0161 276 6440
- Neutrophil function – Tel: 0161 276 6440
Background
Grouping is frequently based on the specific fault in the immune system. This may include:
- B Cell antibody deficiency causes mainly recurrent bacterial infections
- T cell deficiency causes viral, protozoal and fungal infections
- Combined T and B cell deficiencies
- Defective phagocytes
- Complement deficiencies cause mainly bacterial infection
There are no ‘screening tests’ for immune deficiency. In cases with recurrent bacterial infection it may be sensible to start by measuring immunoglobulins, but we advise discussing individual cases early on.
Hereditary angioedema
Relevant immunological tests:
Recurrent abdominal pain and/or deep subcutaneous swellings without urticaria (particular occurring after minor trauma), often with family history, may indicate HAE. C4 and C1 inhibitor will be low.
Uncommonly there may be normal C1INH level with defective function. If C4 is very low without other explanation and C1INH normal, C1INH function will be measured.
Secondary immunodeficiency
Relevant immunological tests:
- Immunoglobulins (IgG, IgA, IgM)
- Monitoring absolute CD4 count (T cell count) (for patients with known HIV serology)
Secondary causes of immunodeficiency are more common than primary causes and levels of immunoglobulins might reflect decreased production (eg. lymphoproliferative disorders, drugs) or increased losses (nephritic syndrome).
In HIV infection the CD4 count is used to monitor progress of disease and inform treatment decisions. Other acute and chronic diseases affect CD4 counts.
In HIV infection they are best done at the same time of day each time and avoiding acute ill health. They should never be done as a substitute to HIV antibody testing to diagnose HIV infection.
Guidelines and information on CD4 counts are available from Aidsmap.
Patient information
Additional patient information is available from:
Acquired C1 esterase inhibitor deficiency
Relevant immunological tests:
Consumption/inactivation of C1INH may occur in SLE and lymphoproliferative disease. This may lead to episodes of angioedema as with the inherited form. C1q is low in acquired C1INH deficiency but usually normal in HAE.
TB exposure: Quantiferon
Relevant immunological tests: Gamma Interferon (Quantiferon)
This test measures gamma interferon produced by T cells in response to M. tuberculosis peptides.
The test is used to help diagnose latent TB infection and is indicated in individuals with a positive delayed hypersensitivity skin test.
The test may produce indeterminate results in patients with active TB and in immune deficiency states.
(Last reviewed June 2019)