Immunoglobulin A (IgA)*

Immunoglobulin A (IgA) is a type of secretory immunoglobulin that plays a key role in defending the body against microorganisms and activating the cellular immune response. The analysis of Immunoglobulin A (IgA) levels in the blood is used in laboratories worldwide, including blood analysis laboratories in Belgrade, such as IntroLab, to assess patients’ immune status.

Importance of IgA

Immunoglobulins are proteins synthesized by plasma cells, which are specific immune system cells, in response to exposure to various microorganisms and foreign substances. IgA is one of the types of immunoglobulins that plays a vital role in protecting the body.

IgA makes up about 15% of all immunoglobulins in the blood, but it is more prevalent in mucous membranes and secretions such as saliva, tears, and milk. The mucous membranes of the respiratory, digestive, and urogenital tracts and the surfaces of the ears and eyes play a crucial role in protecting the body from harmful environmental influences. The first line of defense on these membranes is Immunoglobulin A, secreted by specific plasma cells.

IgA exists in two forms – as a blood monomer and a polymer, or dimer, in secretions that coat mucous membranes. The dimer is formed when a specific J chain and a secretory component link two IgA monomers. This connection allows Immunoglobulin A to perform its primary role in defending against microorganisms and activating the cellular immune response. IgA also effectively neutralizes allergens, antigens, and toxins from food in the digestive tract.

IgA is particularly significant in protecting newborns, as it is the only immunoglobulin in breast milk. This IgA provides passive immunization and protects the newborn from gastrointestinal infections. This is especially important in the first few weeks and months after birth when the child has not yet developed its ability to synthesize Immunoglobulin A. There are two subclasses of IgA – IgA1 and IgA2, which have different action characteristics and the ability to pass through mucous barriers.

When is the Immunoglobulin A analysis indicated?

Determining the level of immunoglobulins in the blood has several specific indications:

• Assessment of immune status: Measuring IgA indicates a patient’s immune status. For example, elevated IgA levels may indicate the presence of an infection, such as sinusitis or a gastrointestinal infection.
• Diagnosis of celiac disease: Celiac disease is an autoimmune disorder caused by gluten sensitivity. IgA-specific antibodies (anti-tTG) may be elevated in individuals with celiac disease. For this reason, this blood analysis is used to confirm the diagnosis.
• Monitoring therapy for immunodeficiencies: Individuals with primary immunodeficiencies who have a compromised immune system may have reduced levels of Immunoglobulin A. Regular measurement of IgA, therefore, allows for monitoring the effectiveness of therapy or the need for additional treatments.
• Identification of allergic conditions: In allergic diseases, such as allergic rhinitis or atopic dermatitis, allergy testing may reveal elevated levels of IgA-specific antibodies (e.g., IgA specific to allergens).
• Diagnosis of IgA nephropathy: IgA nephropathy is a kidney disease characterized by the deposition of IgA antibodies in the kidney glomeruli. The analysis of Immunoglobulin A, as part of an immunological blood analysis, is used for diagnosing this disease and monitoring its progression.

It is important to emphasize that interpreting the results of IgA analysis is complex and should rely on a doctor’s expert evaluation. Considering clinical symptoms, medical history, and other laboratory findings, the doctor will make a final diagnosis and recommend an appropriate treatment plan.