What are the functions of immunoglobulin A?
Immunoglobulin A is primarily responsible for the defense against pathogens on the surface of mucous membranes. After its formation, it is therefore mainly released into secretions (hence also called “secretory IgA”). These are, for example, the secretions of the gastrointestinal tract, vagina, nose and bronchi, as well as tear fluid and breast milk.
Normal values for immunoglobulin A
The following normal values apply for the IgA level in the blood serum (total IgA), depending on age:
- 3 to 5 months: 10 – 34 mg/dl
- 6 to 8 months: 8 – 60 mg/dl
- 9 to 11 months: 11 – 80 mg/dl
- 12 months to 1 year: 14 – 90 mg/dl
- 2 to 3 years: 21 – 150 mg/dl
- 4 to 5 years: 30 – 190 mg/dl
- 6 to 7 years: 38 – 220 mg/dl
- 8 to 9 years: 46 – 250 mg/dl
- 10 to 11 years: 52 – 270 mg/dl
- 12 to 13 years: 58 – 290 mg/dl
- 14 to 15 years: 63 – 300 mg/dl
- 16 to 17 years: 67 – 310 mg/dl
- 18 years and older: 70 – 400 mg/dl
For IgA levels in saliva, the normal range is 8 to 12 mg/dl.
When is IgA deficiency present?
Selective IgA deficiency is the most common congenital immunodeficiency. It is caused by a defective development of certain immune cells. The disorder affects the transformation of B cells into plasma cells, which are actually responsible for the release of IgA.
Decreased immunoglobulin A is also found:
- as a consequence of severe burns,
- in nephrotic syndrome (a form of kidney damage),
- in exudative enteropathy (protein loss through the intestinal mucosa).
What are the symptoms of congenital IgA deficiency?
In most cases, congenital immunoglobulin A deficiency does not cause symptoms. However, in some cases, an increased susceptibility to infections develops. In addition, the following diseases occur more frequently in patients with congenital IgA deficiency:
- autoimmune diseases (such as rheumatoid arthritis or lupus erythematosus)
- allergic conjunctivitis or nasal mucosa inflammation (conjunctivitis, sinusitis)
- hypersensitivity to certain foods
- neurodermatitis
- bronchial asthma
When is immunoglobulin A elevated?
An elevated immunoglobulin A is found, for example, in:
- chronic liver diseases (such as cirrhosis, alcohol-damaged liver)
- @ chronic infections such as HIV
- autoimmune diseases such as celiac disease
In most cases, not only the level of IgA increases in these diseases. Antibodies such as IgG or IgM may also be elevated.
In contrast, in IgA-type monoclonal gammopathy, only the level of IgA is elevated. In this disease, there is an abnormal increase in a clone of IgA.
