Immunoglobulin A (IgA): what is it, interpretation of the results. Immunoglobulin - what is it? Immunoglobulin (analysis): norm and deviations

Immunoglobulin A (IgA) is an indicator of humoral immunity. The main indications for use: assessment of local immunity, the course of infectious processes, diseases of the liver, kidneys, chronic inflammation.

Immunoglobulins (antibodies) involved in providing local immunity.

Serum IgA is a fraction of gamma globulins and makes up 10-15% of the total amount of all soluble immunoglobulins. IgA are found mainly in the gastrointestinal tract and secretions (bronchial, cervical, etc.). In blood serum, IgA is represented mainly by monomeric molecules. The main amount of IgA (secretory IgA) is not in the serum, but on the surface of the mucous membranes, is found in milk, colostrum, saliva, lacrimal, bronchial and gastrointestinal secretions, bile, urine. In mucosal secretions, IgA is present in the form of dimers of two monomeric units containing two heavy and two light chains, non-covalently linked by a secretory component. The secretory component - a small polypeptide, 60 kDa - is produced by epithelial cells of the mucous membranes and secretory glands, facilitates the transport of IgA through the epithelium and protects immunoglobulin molecules from cleavage by digestive enzymes. The half-life of antibodies of this class from the blood is 4-5 days.

Why is it important to do Immunoglobulin A (IgA)?

The main function of serum IgA is to provide local immunity, protection of the respiratory, genitourinary and gastrointestinal tract from infections. Secretory antibodies have a pronounced anti-adsorption effect: they prevent bacteria from attaching to the surface of epithelial cells, prevent adhesion, without which bacterial cell damage becomes impossible. Together with non-specific immunity factors, they protect the mucous membranes from microorganisms and viruses. IgA deficiency (congenital or acquired) can lead to repeated infections, autoimmune disorders, and allergies.

IgA does not pass through the placental barrier, its level in newborns is about 1% of the concentration in adults, by the first year of life this figure is only 20% of the adult level. In the first days of life, secretory IgA enters the child's body with the mother's colostrum, protecting the child's respiratory tract and gastrointestinal tract. The age of 3 months is defined by many authors as a critical period; this period is especially important for the diagnosis of congenital or transient insufficiency of local immunity. The level of IgA, characteristic of an adult, the child reaches about 5 years of age.

Assessment of the course of diseases occurring with activation of immunity

Acute and chronic infections of viral and bacterial etiology.
Bronchial asthma.
Oncological diseases of the lymphatic system (leukemia, multiple myeloma).
Connective tissue diseases (systemic lupus erythematosus, rheumatoid arthritis and others).

What diseases are treated with Immunoglobulin A (IgA)?

To check/improve the performance of which organs, I need to do Immunoglobulin A (IgA)?

Liver, stomach, intestines, lymphatic system.

How does Immunoglobulin A (IgA) work?

Blood sampling is performed in an empty test tube or with gel (serum production).
In patients with low levels of immunoglobulins, especially IgG and IgM, it is important to take measures to prevent bacterial infection. When caring for a patient, the symptoms of infection (fever, chills, skin rash, and skin ulceration) should be carefully considered.
A patient with elevated immunoglobulin levels and symptoms of monoclonal gammopathy should be warned to report bone pain and tenderness in a timely manner. In such patients, the bone marrow contains many malignant plasma cells that produce antibodies and inhibit the process of hematopoiesis. Particular attention should be paid to signs of hypercalcemia, renal failure and spontaneous fractures.
The venipuncture site is pressed down with a cotton ball until bleeding stops.
When a hematoma forms at the venipuncture site, warm compresses are prescribed.
After taking blood, the patient can return to his usual diet and continue taking medications.

How to prepare for the delivery of Immunoglobulin A (IgA)?

It should be explained to the patient that the analysis is necessary to determine the level of antibodies, and if he is receiving therapy aimed at increasing immunity, then also to monitor the effectiveness of therapy.
The patient should refrain from eating for 12-14 hours before the study is allowed to drink water.
The patient should be warned that a blood sample will be required for analysis and should be told who will perform the venipuncture and when.
It should be warned about the possibility of discomfort during the application of a tourniquet on the arm and venipuncture.
You should find out if the patient is taking drugs that can affect the result of the analysis.
Please note that the use of alcohol and drugs can affect the result of the analysis.

- a group of primary immunodeficiency states, which are caused by impaired synthesis or accelerated destruction of immunoglobulin molecules of this class. Symptoms of the disease are frequent bacterial infections (especially of the respiratory system and ENT organs), gastrointestinal disorders, allergies, and autoimmune lesions. Immunoglobulin A deficiency is diagnosed by determining its amount in the blood serum, and molecular genetic techniques are also used. Symptomatic treatment is reduced to the prevention and timely treatment of bacterial infections and other disorders. In some cases, immunoglobulin replacement therapy is carried out.

Immunoglobulin A deficiency is a polyetiological form of primary immunodeficiency, in which there is a lack of this class of immunoglobulins with a normal content of the remaining classes (G, M). Deficiency can be complete, with a sharp decrease in all fractions of globulin A, and selective, with a lack of only certain subclasses of these molecules. Selective immunoglobulin A deficiency is a very common condition, according to some reports, its occurrence is 1:400-600. The manifestations of immunodeficiency with a selective deficiency of the compound are rather blurred; in almost two-thirds of patients, the disease is not diagnosed, since they do not seek medical help. Immunologists have found that immunoglobulin A deficiency can manifest itself not only with infectious symptoms, but patients also often have metabolic and autoimmune disorders. Given this circumstance, it can be assumed that the occurrence of this condition is even higher than previously thought. Modern geneticists believe that the disease occurs sporadically or is a hereditary pathology, and both autosomal dominant and autosomal recessive inheritance can act as a transmission mechanism.

Causes of immunoglobulin A deficiency

The etiology and pathogenesis of both complete and selective immunoglobulin A deficiencies have not been fully determined to date. So far, only the genetic and molecular mechanisms of individual forms of the disease have been established. For example, selective deficiency of type 2 immunoglobulin A is caused by mutations in the NFRSF13B gene, located on the 17th chromosome and encoding the protein of the same name. This protein is a transmembrane receptor on the surface of B-lymphocytes, responsible for the recognition of tumor necrosis factor and some other immunocompetent molecules. The compound is actively involved in the regulation of the intensity of the immune response and the secretion of various classes of immunoglobulins. According to molecular studies, a genetic defect in the TNFRSF13B gene, leading to the development of an abnormal receptor, makes certain fractions of B-lymphocytes functionally immature. Such cells, instead of producing optimal amounts of immunoglobulins A, secrete a mixture of classes A and D, which leads to a decrease in the concentration of class A.

Mutations in the TNFRSF13B gene are a common, but far from the only, cause of the development of immunoglobulin A deficiency. In the absence of damage to this gene and with the presence of clinical manifestations of this type of immunodeficiency, the presence of mutations in the 6th chromosome, where the genes of the major histocompatibility complex (MCHC) are located, is assumed. In addition, in a number of patients with immunoglobulin A deficiency, deletions of the short arm of the 18th chromosome are observed, but so far it has not been possible to unequivocally link these two circumstances with each other. Sometimes the lack of class A molecules is combined with a deficiency of immunoglobulins of other classes and a violation of the activity of T-lymphocytes, which forms the clinical picture of common variable immunodeficiency (CVID). Some geneticists suggest that immunoglobulin A deficiency and CVID are caused by very similar or identical genetic defects.

Immunoglobulin A differs from other related molecules in that it causes the very first stage of nonspecific immunological defense of the body, since it is secreted as part of the secretion of the glands of the mucous membranes. With its deficiency, it becomes easier for pathogenic microorganisms to infiltrate the weakly protected delicate tissues of the mucous membranes of the respiratory tract, gastrointestinal tract and ENT organs. The mechanisms of autoimmune, metabolic and allergic disorders in immunoglobulin A deficiency are still unknown. There is an assumption that its low concentration introduces an imbalance in the entire immune system.

Symptoms of immunoglobulin A deficiency

All manifestations of immunoglobulin A deficiency in immunology are divided into infectious, metabolic (or gastrointestinal), autoimmune and allergic. Infectious symptoms consist in an increased frequency of bacterial infections of the respiratory tract - patients often experience laryngitis, tracheitis, bronchitis and pneumonia, which can take a severe course and be accompanied by the development of complications. In addition, immunoglobulin A deficiency is characterized by a rapid transition of acute inflammatory processes into chronic forms, which is especially indicative of lesions of the upper respiratory tract - patients are often diagnosed with otitis, sinusitis and frontal sinusitis. Quite often occurring combined deficiency of immunoglobulins A and G2 leads to severe obstructive pulmonary lesions.

To a lesser extent, infectious lesions affect the gastrointestinal tract. With a deficiency of immunoglobulin A, there is a slight increase in giardiasis, gastritis and enteritis can be recorded. The most characteristic symptoms of this immunodeficiency on the part of the gastrointestinal tract are lactose intolerance and celiac disease (immunity of cereal gluten protein), which, in the absence of nutritional correction, can lead to atrophy of the intestinal villi and malabsorption syndrome. Among patients with deficiency of immunoglobulin A, ulcerative colitis, biliary cirrhosis of the liver and chronic hepatitis of autoimmune genesis are also often recorded. These diseases are accompanied by pain in the abdomen, frequent episodes of diarrhea, weight loss and hypovitaminosis (due to malabsorption of nutrients due to malabsorption).

In addition to the diseases of the gastrointestinal tract described above, autoimmune and allergic lesions in immunoglobulin A deficiency are manifested by an increased incidence of systemic lupus erythematosus and rheumatoid arthritis. Thrombocytopenic purpura and autoimmune hemolytic anemia are also possible, often with a severe course. In more than half of patients, autoantibodies against their own immunoglobulin A are determined in the blood, which further exacerbates the phenomenon of a lack of this compound. In patients with immunoglobulin A deficiency, urticaria, atopic dermatitis, bronchial asthma and other diseases of allergic origin are often detected.

Diagnosis of immunoglobulin A deficiency

Diagnosis of immunoglobulin A deficiency is made on the basis of the patient's medical history (frequent infections of the respiratory tract and ENT organs, gastrointestinal lesions), but the most accurate way to confirm the diagnosis is to determine the amount of serum immunoglobulins of different classes. In this case, an isolated decrease in the level of this component of humoral immunity below 0.05 g/l can be detected, which indicates its deficiency. Against this background, the level of immunoglobulins G and M remains within the normal range, sometimes a decrease in the G2 fraction is detected. With a partial deficiency of immunoglobulin A, its concentration remains in the range of 0.05-0.2 g / l. When evaluating the results of the analysis, it is important to remember the age-related characteristics of the amount of globulins in the blood plasma - for example, the concentration of fraction A 0.05-0.3 g / l in children under 5 years of age is called a transient deficiency and may disappear in the future.

Sometimes a partial deficiency of immunoglobulin A is found, in which its amount in plasma is reduced, but the concentration of the compound in the secretions of the mucous membranes is quite high. There are no clinical symptoms of the disease in patients with partial deficiency. In the immunogram, attention should be paid to the number and functional activity of immunocompetent cells. With immunoglobulin A deficiency, the number of T- and B-lymphocytes is usually maintained at a normal level, a decrease in the number of T-lymphocytes indicates the possible presence of a common variable immunodeficiency. Among other diagnostic methods, the determination of antinuclear and other autoantibodies in plasma, automatic sequencing of the TNFRSF13B gene and allergological tests play a supporting role.

Treatment, prognosis and prevention of immunoglobulin A deficiency

There is no specific treatment for this immunodeficiency; in some cases, immunoglobulin replacement therapy is performed. Antibiotics are mainly used to treat bacterial infections, sometimes prophylactic courses of antibacterial agents are prescribed. It is necessary to correct the diet (exclusion of hazardous foods) with the development of food allergies and celiac disease. In the latter case, cereal-based dishes are excluded. Bronchial asthma and other allergic pathologies are treated with conventional drugs - antihistamines and bronchodilators. With severe autoimmune disorders, immunosuppressive drugs are prescribed - corticosteroids and cytostatics.

The prognosis for immunoglobulin A deficiency is generally favorable. In many patients, the pathology is completely asymptomatic and does not require special treatment. With an increase in the frequency of bacterial infections, autoimmune lesions and malabsorption disorders (malabsorption syndrome), the prognosis may worsen according to the severity of the symptoms. To prevent the development of these manifestations, it is necessary to use antibiotics at the first signs of an infectious process, adherence to the rules regarding diet and diet composition, regular monitoring by an immunologist and doctors of other specialties (depending on concomitant disorders). Care should be taken when transfusing whole blood or its components - in rare cases, patients experience an anaphylactic reaction due to the presence of autoantibodies to immunoglobulin A in the blood.

Immunoglobulin A is an indicator of humoral immunity. It is determined to assess local immunity, the course of acute infectious processes, diseases of the kidneys, liver, and chronic inflammation. In the Yusupov hospital, laboratory assistants use high-quality reagents to determine the level of immunoglobulins A. The results of the study are interpreted by professors and doctors of the highest category. Immunologists carry out therapy aimed at normalizing the concentration of immunoglobulins A. Therapists use effective drugs registered in the Russian Federation, which have minimal side effects.

Immunoglobulins A are proteins that provide local immunity. They are represented in the human body by two fractions: serum, providing local immunity, and secretory. The secretory fraction is found in milk, respiratory and intestinal secretions, lacrimal fluid and saliva, which, together with non-specific immunity factors, protect the protection of mucous membranes from viruses and bacteria.

Functions of immunoglobulin A

Serum immunoglobulin A is a fraction of gamma globulins. It makes up 10-15% of the total amount of all soluble immunoglobulins. In blood serum, immunoglobulin A is represented mainly by monomeric molecules. The main amount of immunoglobulin A is not in the blood serum, but on the surface of the mucous membranes. Secretory immunoglobulin facilitates the transport of immunoglobulin A across the epithelium. It protects immunoglobulin molecules from cleavage by digestive tract enzymes.

The main function of serum immunoglobulin A is to provide local immunity, protect the genitourinary, respiratory tract and digestive organs from pathogens of infectious diseases. Secretory antibodies have a pronounced anti-adsorption effect: they prevent the attachment of bacteria to the surface of epithelial cells, prevent the adhesion of microorganisms, without which bacterial damage to the cell becomes impossible. Also, immunoglobulins A, together with non-specific immunity factors, protect the mucous membranes from microorganisms. Congenital or acquired deficiency of immunoglobulin IgA can lead to allergies, autoimmune disorders, allergies, repeated infections.

Immunoglobulin A does not cross the placental barrier. Its level in newborns is about 1% of the concentration in adults. By the first year of a child's life, this figure is 20% of the adult level. After the birth of a baby, secretory immunoglobulins enter his body with the mother's colostrum. They protect the gastrointestinal tract and respiratory tract of the child. The age of 3 months is critical. During this period, doctors diagnose congenital or transient insufficiency of local immunity. By the age of five, the level of immunoglobulin A reaches the concentration characteristic of an adult.

The norm of immunoglobulin A in children depends on their age. In children from 3 to 12 months old, it is 0.02-0.05 g / l, from 12 to 16 years old it is in the range of 0.6-3.48 g / l. In adults over 20 years of age, the normal level of immunoglobulin A varies from 0.9 to 4.5 g / l.

Indications for the study of immunoglobulin A

With the help of immunoglobulins A, doctors assess the course of diseases that occur with the activation of immunity:

acute and chronic infections of bacterial and viral origin; bronchial asthma;
oncological diseases of the lymphatic system (leukemia, multiple myeloma);
connective tissue diseases (systemic lupus erythematosus, rheumatoid arthritis).

Immunoglobulin IgA is determined in the presence of the following diseases:

recurrent bacterial respiratory infections (sinusitis, pneumonia), as well as otitis and meningitis, bronchial asthma;
chronic diarrhea, malabsorption syndrome;
anaphylactic post-transfusion reactions;
Louis Bar syndrome (ataxia - telangiectasia);
tumor diseases of the lymphoid system (myeloma, leukemia, reticulosarcoma, lymphoma).
chronic hepatitis, cirrhosis of the liver.

Using the study of IgA immunoglobulin, doctors at the Yusupov hospital check the functioning of the liver, stomach, intestines, and lymphatic system.

Collection of biomaterial for research

In order to determine the level of immunoglobulin A, venous blood is taken into an empty tube or with a gel (to obtain serum). Patients with a low level of immunoglobulins on the eve of the study should observe measures to prevent bacterial infection. The venipuncture site is pressed down with a cotton ball until bleeding stops. If a hematoma has formed at the site of the vein puncture. Apply a warm compress.

The patient is advised to refrain from eating for 12-14 hours before the study. He can drink pure non-carbonated water. Doctors stop medications that may affect the results of the study. 3 days before blood sampling, the patient must stop drinking alcohol. The results of the analysis can be obtained after 4 hours.

Causes of an increase in immunoglobulin A in adults

Immunoglobulins A bind to microorganisms and delay their attachment to the cell surface. A decrease in the content of immunoglobulins A indicates a lack of local and general immunity. Their concentration increases with the following diseases:

The level of immunoglobulin A decreases in patients suffering from diseases that deplete the immune system. May be IgA is low in a child with an early viral infection

Decrease in the level of immunoglobulin A

Immunoglobulin A is lowered in patients with neoplasms of the lymphatic system, lymphoproliferative diseases, pernicious anemia, hemoglobinopathies. The content of immunoglobulin A decreases after splenectomy, in case of protein loss in enteropathies and nephropathies. Treatment with immunosuppressants, cytostatics, exposure to ionizing radiation can also reduce the level of immunoglobulin IgA.

Long-term exposure to benzene, toluene, xylene, medications: dextran, estrogens, methylprednisolone, carbamazepine, gold preparations, valproic acid can lower the level of immunoglobulin A. Get a consultation with an immunologist by making an appointment by calling the Yusupov Hospital. The doctor will conduct an examination, prescribe a study of the level of immunoglobulin A.

Bibliography

ICD-10 (International Classification of Diseases)
Yusupov hospital
"Diagnostics". - Brief Medical Encyclopedia. - M.: Soviet Encyclopedia, 1989.
"Clinical evaluation of the results of laboratory studies" / / G. I. Nazarenko, A. A. Kishkun. Moscow, 2005
Clinical laboratory analytics. Fundamentals of clinical laboratory analysis V.V. Menshikov, 2002.

Prices for diagnostic studies

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Secretory immunoglobulin A is the humoral component of the immune system. When a foreign agent enters the surface of the mucous membranes, antibodies begin an immune response. Studies directed to determine the level of this substance are prescribed for suspected diseases that lead to a decrease in the reactivity of the body. An insufficient amount of immunoglobulins leads to frequent respiratory diseases, inflammatory processes in the reproductive system and chronic diarrhea.

Forms

In humans, this substance exists in the body in several forms: secretory and serum. Secretory lgA takes part in the local immune response. In its composition, it contains an additional secretory component, which is reproduced in the epithelial cells of the mucous membranes. When the substance passes through the cells, the secretory component is attached. It is necessary to ensure the stability of lgA immunoglobulin in milk, bile, vaginal secretions, lacrimal fluid, saliva, organs of the respiratory and digestive tract. Class A secretory antibodies protect the body from the effects of foreign agents such as bacteria, viruses, fungi and allergens.

When a foreign microorganism enters the surface of the mucous membranes, secretory immunoglobulin begins to bind to antigens that have already appeared. The resulting complex prevents the adhesion of foreign agents to the surface of the mucous membranes. Thus, the pathogenic microorganism does not penetrate into the internal environment of the body.

If there is a deficiency of secretory immunoglobulin A in the body, then frequent relapses of diseases occur.

Serum immunoglobulin in the body is much less than secretory. The fraction of gamma globulins is about 10% of the total amount of antibodies. The formation of serum immunoglobulin A occurs in mature cells of B-lymphocytes. The vast majority of this substance is localized in the gastrointestinal tract. Activation of the compliment system occurs via an alternative pathway. The level of these antibodies is not controlled by the thymus and in childhood its amount is not enough to ensure the normal protective functions of the body. The determination of serum immunoglobulin A is a diagnostic marker for certain diseases of the immune system.

Indications for analysis

Cases in which an analysis for the level of antibodies of class A is indicated:

the presence of systemic diseases;
diarrhea;
diseases of the blood and liver;
oncology;
frequent relapses of diseases;
Allergic reactions of immediate type.

Norms

Before we talk about pathological conditions that lead to a deviation of the indicator from the norm, let's talk about the norms. To study the level of secretory immunoglobulin A, saliva is usually used. The norm of this indicator for both men and women is from 40 to 170 mcg / ml. For better orientation in the results of the study of serum class A antibodies, we have compiled a table:

Indicators in children

The level of immunoglobulin alpha in the blood of children differs from that of an adult. In a newborn, its amount is very small. This is due to the fact that the child was not in contact with the environment. Breastfeeding is especially important in the first 4 months of a baby's life because it allows the antibody levels to rise. In a child's body, the synthesis of this substance occurs in small quantities, and at the age of 12 months its rate reaches 20% of the adult norm.

Level up

This substance does not have a special memory and therefore, with repeated damage to the body, its high level is observed. If, as a result of the study, a sharp increase in the indicator is noticeable, which indicates the presence of an acute inflammatory process in the body.

The level of immunoglobulin A may be elevated when:

A decrease in the level of immunoglobulin A may be due to the presence of pathological processes in the body, such as:

inflammatory processes in the large intestine, which most often occur after suffering acute intestinal infections;
congenital insufficiency of the humoral link of immunity;
celiac disease;
selective deficiency of immunoglobulin A;
hypoplasia of the thymus;
HIV infection and AIDS;
tumor processes in the lymphatic system (lymphoma);
kidney disease with nephrotic syndrome;
ataxia;
pregnancy;
burn disease;
oncology treatment using radioactive irradiation;
intoxication;
treatment with cytostatics;
chronic inflammatory processes in the respiratory system;
postoperative period after removal of the spleen;
helminths (giardiasis).

Result error

To obtain reliable results, it is necessary to adhere to the basic rules for passing all tests. The blood test has a high accuracy of the study, but errors are possible. The results of the study can be distorted by alcohol abuse and medication (immunosuppressants, estrogens, gold preparations), severe kidney disease, burns, removal of the spleen, exposure to ionizing radiation. Immunoglobulin A may be lowered if a person has been vaccinated or taken immunoglobulins in the last 6 months.

Among the known immunodeficiency states, selective immunoglobulin A (IgA) deficiency is the most common in the population. In Europe, its frequency is 1/400-1/600 people, in Asia and Africa, the frequency of occurrence is somewhat lower.

Pathogenesis of selective immunoglobulin A deficiency

The molecular genetic basis of IgA deficiency is still unknown. It is assumed that a functional defect in B cells lies in the pathogenesis of the defect, as evidenced, in particular, by a decrease in IgA-expressing B cells in patients with this syndrome. It has been shown that in these patients, many IgA-positive B lymphocytes have an immature phenotype, expressing both IgA and IgD. This is probably due to a defect in the factors that affect the functional aspects of switching the expression and synthesis of IgA by B cells. Defects in both the production of cytokines and disturbances in the response of B cells to various mediators of the immune system will help. The role of such cytokines as TGF-b1, IL-5, IL-10, as well as the CD40-CD40 ligand system is considered.

Most cases of IgA deficiency occur sporadically, but familial cases have also been noted, where the defect can be traced over many generations. Thus, 88 family cases of IgA deficiency are described in the literature. Autosomal recessive and autosomal dominant forms of inheritance of the defect, as well as an autosomal dominant form with incomplete expression of the trait, were noted. In 20 families, different members had both selective IgA deficiency and common variable deficiency (CVID), which suggests a common molecular defect in these two immunodeficiency states. Recently, researchers have become increasingly convinced that selective IgA deficiency and CVID are phenotypic manifestations of the same, as yet unidentified, genetic defect. Due to the fact that the gene suffering from IgA deficiency is not known, several chromosomes are being investigated, the damage of which can presumably be involved in this process.

The main attention is paid to chromosome 6, where the genes of the major histocompatibility complex are located. Some studies indicate the involvement of class III MHC genes in the pathogenesis of IgA deficiency.

Deletions of the short arm of chromosome 18 occur in half of the cases of IgA deficiency, but the exact localization of the breakdown in most patients has not been described. In other cases, studies have shown that the location of the chromosome 18 arm deletion does not correlate with the phenotypic severity of immunodeficiency.

Symptoms of Selective Immunoglobulin A Deficiency

Despite the high prevalence of such immunodeficiency as Selective IgA deficiency, often people with this defect do not have clinical manifestations. This is probably due to various compensatory capabilities of the immune system, although this question remains open today. With a clinically pronounced selective IgA deficiency, the main manifestations are bronchopulmonary, allergic, gastroenterological and autoimmune diseases.

infectious symptoms

Some studies have noted that respiratory tract infections are more common in patients with IgA deficiency and reduced or absent secretory IgM. It is not excluded that only the combination of IgA deficiency and one or more IgG subclasses, which occurs in 25% of patients with IgA deficiency, leads to serious bronchopulmonary diseases.

The most common diseases associated with IgA deficiency are infections of the upper and lower respiratory tract. In general, the causative agents of infections in such cases are bacteria with low pathogenicity: Moraxella catharalis, Streptococcus pneumoniae, Hemophilus influenzae, often causing otitis, sinusitis, conjunctitis, bronchitis and pneumonia in these patients. There are reports that the clinical manifestation of IgA deficiency requires a deficiency of one or more subclasses of IgG, which occurs in 25% of cases of IgA deficiency. Such a defect leads to serious bronchopulmonary diseases, such as frequent pneumonia, chronic obstructive pulmonary disease, chronic bronchitis, bronchiectasis. The most unfavorable is the combined deficiency of IgA and IgG2 subclass, which, unfortunately, is the most common.

Patients with selective IgA deficiency often suffer from various gastrointestinal diseases, both infectious and non-infectious. Thus, among these patients, infection is common Gardia Lamblia(giardiasis). Other intestinal infections are not uncommon. Probably, a decrease in secretory IgA, which is part of local immunity, leads to more frequent infection and multiplication of microorganisms in the intestinal epithelium, as well as to frequent reinfection after adequate treatment. The consequence of chronic intestinal infection is often lymphoid hyperplasia, accompanied by malabsorption syndrome.

Gastrointestinal lesions

Lactose intolerance is also more common than in the general population in selective IgA deficiency. Various diarrheas associated with IgA deficiency, nodular lymphoid hyperplasia, and malabsorption usually respond poorly to treatment.

Noteworthy is the frequent combination of celiac disease and IgA deficiency. Approximately 1 in 200 patients with celiac disease have this immunological defect (14,26). This association is unique, as celiac disease has not yet been associated with any other immunodeficiencies. A combination of IgA deficiency with autoimmune diseases of the gastrointestinal tract has been described. Common conditions include chronic hepatitis, biliary cirrhosis, pernicious anemia, ulcerative colitis, and enteritis.

Allergic diseases

Most clinicians believe that IgA deficiency is accompanied by an increased frequency of almost the entire spectrum of allergic manifestations. These are allergic rhinitis, conjunctivitis, urticaria, atopic dermatitis, bronchial asthma. Many experts argue that bronchial asthma in these patients has a more refractory course, which may be due to the development of frequent infectious diseases in them, exacerbating asthma symptoms. However, there have been no controlled studies on this topic.

Autoimmune pathology

Autoimmune pathology affects not only the gastrointestinal tract of patients with IgA deficiency. Often these patients suffer from rheumatoid arthritis, systemic lupus erythematosus, autoimmune cytopenias.

Anti-IgA antibodies are found in patients with IgA deficiency in more than 60% of cases. The etiology of this immune process is not fully understood. The presence of these antibodies can cause anaphylactic reactions during transfusion of IgA-containing blood products to these patients, however, in practice, the frequency of such reactions is quite low and amounts to about 1 per 1,000,000 blood products administered.

Diagnosis of selective immunoglobulin A deficiency

In the study of humoral immunity in children, quite often one has to deal with a reduced level of IgA against the background of normal levels of IgM and IgG. Available transient IgA deficiency, at which serum IgA was shown, as a rule, are in the range of 0.05-0.3 g / l. More often, this condition is observed in children under 5 years of age and is associated with the immaturity of the immunoglobulin synthesis system.

At partial IgA deficiency the level of serum IgA, although below age-related fluctuations (less than two sigma deviations from the norm), still does not fall below 0.05 g/l. Many patients with partial IgA deficiency have normal levels of secretory IgA in saliva and are clinically healthy.