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Immunoglobulin A, known mainly as IgA, is a protein found in large amounts in the mucous membranes, mainly in the respiratory and gastrointestinal mucosa, in addition to being also found in breast milk, which can be passed to the baby during breastfeeding and stimulating the development of immune system.
This immunoglobulin has the main function of defending the organism and, therefore, when in lower concentrations, it can favor the development of infections, which must be identified and treated according to the doctor's guidance.
What is IgA for
IgA's main function is to protect the body against infections and can initially be obtained through breastfeeding, in which the mother's immunoglobulins are transmitted to the baby. This protein can be classified into two types according to its location and characteristics, and may have different functions that are important for the defense of the organism:
- IgA 1, which is mainly present in serum and is responsible for immunological protection, because it is able to neutralize toxins or other substances produced by invading microorganisms;
- IgA 2, which is present in the mucous membranes and is found associated with a secretory component.This type of IgA is resistant to most proteins produced by bacteria that are responsible for the destruction of the body's cells and, therefore, corresponds to the first line of defense against infectious agents that enter the body through the mucous membranes.
Immunoglobulin A can be found in tears, saliva and breast milk, as well as being present in the genitourinary, digestive and respiratory systems, protecting these systems against infections.
See also how the immune system works.
What can be high IgA
The increase in IgA can happen when there are changes in the mucous membranes, especially in the gastrointestinal and respiratory mucous membranes, since this immunoglobulin is found mainly in that location. Thus, the amount of IgA may be increased in case of respiratory or intestinal infections and in liver cirrhosis, for example, in addition to there may also be changes in case of infections in the skin or kidneys.
It is important that other tests are performed to identify the cause of high IgA and, thus, the most appropriate treatment can be started.
What can be low IgA
The decrease in the amount of circulating IgA is usually genetic and does not lead to the development of symptoms related to this change, being considered deficiency when the concentration of this immunoglobulin is less than 5 mg / dL in the blood.
However, the low amount of this circulating immunoglobulin in the body can favor the development of diseases, since the mucous membranes are unprotected. Thus, in addition to being reduced due to genetic factors, IgA deficiency can also be present in case of:
- Immunological changes;
- Asthma;
- Respiratory allergies;
- Cystic fibrosis;
- Leukemia;
- Chronic diarrhea;
- Malabsorption syndrome;
- Newborns with rubella;
- People who have undergone bone marrow transplantation;
- Children infected with the Epstein-Barr virus.
Normally, when there is a decrease in IgA, the body tries to compensate for this decrease by increasing the production of IgM and IgG in order to fight the disease and keep the body protected. It is important that, in addition to IgA, IgM and IgG measurements, more specific tests are carried out to identify the cause of the alteration and, thus, initiate the most appropriate treatment. Learn more about IgM and IgG.