PIDs can be categorised into four groups according to what part of the immune system is affected:
Antibodies are proteins made by specialized white blood cells: B cells (B lymphocytes) and plasma cells. The function of antibodies is to recognise infectious agents so that they can be blocked. Antibody Deficiencies include:
- Common Variable Immune Deficiency
- Transient Hypogammaglobulinaemia of infancy
- X-linked Agammaglobulinaemia
- Hyper IgM Syndrome
- Selective IgA Deficiency
- IgG Subclass Deficiency
- Specific Antibody Deficiency
- Hyper IgE Syndrome
- WHIM Syndrome
T cells (T lymphocytes) are specialised white blood cells that are critical to a healthy immune system. People who lack T cells also tend to have weak antibody defences, and this is called combined immunodeficiency. These disorders are very rare and hereditary. Combined Immune Deficiencies include:
- SCID (Severe Combined Immune Deficiency)
- DiGeorge Syndrome
- Ataxia Telangiectasia
- Wiskott-Aldrich Syndrome
- Hyper IgM syndrome
Phagocytes include white blood cells (neutrophils and macrophages) that engulf and kill antibody coated foreign invaders. Phagocytes can be defective either in their ability to kill pathogens or in their ability to move to the site of an infection. In either case, the defect results in increased infections. Phagocytic Cell Deficiencies include:
The complement system consists of a group of proteins that attach to antibody coated foreign invaders like bacteria and viruses. People with complement deficiencies may develop antibodies that react against the body’s own cells and tissues.
IDF_Patient_Family_Handbook_5th_Edition Complement Deficiencies describes the following:
- Deficiencies in the classical pathway: C1q, C1r, C1s, C4, C2, C1-Inh, Hereditary Angioedema
- Deficiencies of the Lectin pathway components: MBL Deficiency, M-ficolin, H-ficolin, CL-11, MASPs
- Deficiencies of the Alternative Pathway: Factors D, B and Prpoerdin
In order for our bodies to have different types of cells, there has to be a mechanism for controlling the expression of our genes. In some cells, certain genes are turned off, while in other cells they are transcribed and translated into proteins.
Transcription factors (TFs) are molecules involved in regulating gene expression. This allows differentiation into the various types of cells, tissues, and organs that make up our bodies.
Resources for further reference:
For comprehensive information, order the IDF Patient and Family Handbook Australasian Edition with over 250 pages of PID information.
IDFA’s list of booklets and brochures for primary immune deficiencies
To understand how the immune system works and PIDs occur, read Sara LeBien’s booklet Our Immune System IDF US, Sara LeBien. This booklet is wonderful for explaining how the immune system works for both children and adults alike. PDF format, 2.3 MB.
About recurrent infections and PID read IDF NZ Re-current Infections and Immune Deficiency IDF New Zealand booklet about re-current infections and Immune Deficiency, PDF format, 251 KB.
Check our research journals and papers