Immunoglobulin D is one of the least numerous and, at the same time, the most mysterious antibodies in the human body. Research shows that increased levels of IgD antibodies are associated with some infectious and immune-related diseases, but its exact role in these pathologies remains unclear.

Type D immunoglobulin (IgD) , or D type antibody, is an immune protein produced by B lymphocytes. IgD antibody is one of the least numerous and its concentration in the blood is 0 .04 mg / ml. Thus, it accounts for 1% of all classes of antibodies in the blood.

An IgD antibody also has a very short half-life in the body as it is sensitive to proteolytic (protein-breaking) enzymes.

Immunoglobulin type D (IgD) - types

The IgD antibody in the human body exists in two forms. The first type is an IgD antibody bound to cell membranes, which, together with the IgM antibody, is found on the surface of mature B lymphocytes before stimulation by antigen (so-called virgin B lymphocytes).

The second type is an IgD antibody not related to cell membranes, i.e. free figure. Free IgD antibody is found in blood and secretions, e.g. saliva.

IgD antibody, like all other classes of antibodies, is divided into total and specific. Specific IgD antibodies are produced throughout life after contact with various antigens.

In contrast, all specific IgD antibodies in the body constitute the pool of total IgD antibodies.

Immunoglobulin type D (IgD) - role in the body

Although the IgD antibody was discovered in 1965, its exact role in the body remains unclear. The IgD antibody has the ability to bind bacteria and viruses, which supports the body's mucosal defense.

Most likely for this reason, the number of B lymphocytes synthesizing IgD antibodies increases in people with impaired mucosal defense, e.g. IgA antibody deficiency.

Studies in laboratory mice have shown that in animals deficient in IgM antibodies, IgD is able to replace almost all biological functions of IgM.

In addition, it is believed that the IgD antibody may have properties that enhance the action of other classes of antibodies (IgM, IgG, IgA) and inhibitmultiplication of viruses in the body. It is also involved in the so-called immune memory by supporting memory cells.

Immunoglobulin type D (IgD) - indications for the test

The increase or decrease in the amount of IgD antibodies in the blood is probably not of great clinical significance. Clinical conditions in which the assessment of his height may be important are:

  • diagnosis of IgD myeloma
  • monitoring IgD myeloma therapy
  • periodic fever related to hypergammaglobulinemia D

Immunoglobulin type D (IgD) - what is the test?

Testing the concentration of total IgD antibodies is performed from venous blood taken from the elbow flexion. The concentration of IgD antibodies is very often measured together with other classes of antibodies (IgG, IgM, IgA).

The most frequently used method for the determination of IgD antibodies is radial immunodiffusion (RID). The RID method is based on the assessment of the concentration of antibodies by measuring the radius that is formed as a result of the reaction of IgD antibodies with the antigen contained in a gel carrier.

The immunonephelometric method is also used to determine the concentration of IgD antibodies. It should be emphasized, however, that currently there is no single recommended laboratory method for the determination of IgD antibodies.

Immunoglobulin type D (IgD) - norm

Norms for IgD antibodies are very difficult to establish because their distribution in the population is more varied than in other classes of antibodies. Due to this, the norm for total IgD is very broad and ranges from 1.3 to 152.7 mg / l.

Immunoglobulin type D (IgD) - results. What does lowered IgD mean?

Too low IgD level can be caused by:

  • selective immunoglobulin D deficiency
  • non-IgD myeloma

Immunoglobulin type D (IgD) - results. What does elevated IgD mean?

Research shows that an increase in the level of IgD antibodies in the blood may be characteristic of some pathologies:

  • IgD myeloma
  • periodic fever associated with hypergammaglobulinemia D
  • early stages of infections e.g. Mycobacterium pneumoniae, rubella, measles
  • chronic infections e.g. leprosy, tuberculosis, salmonellosis, malaria
  • immunodeficiency syndromes, e.g. Nezelof's syndrome, ataxia-telangiectasia syndrome
  • allergic bronchopulmonary aspergillosis
  • allergic diseases, e.g. atopic dermatitis
  • sarcoidosis
  • AIDS
  • autoimmune diseases, e.g. rheumatoid arthritis, lupusSystemic Erythematosus
  • IgD antibody levels have also been shown to be higher in smokers than in non-smokers

However, it should be noted that the exact clinical significance and reasons for the increase in IgD levels in most of the above situations has not yet been established.

Hypergammaglobulinemia-related period fever D

The periodic fever associated with hypergammaglobulinemia D, or HIDS for short, is a genetically determined disease with an increase in the level of IgD antibodies.

The cause of HIDS is a mutation of the gene encoding the enzyme mevalonate kinase, the deficiency of which causes the accumulation of mevalonic acid in the body. One of the markers of the diagnosis of the disease is the increased level of IgD antibodies in the blood, and often also IgA.

A characteristic symptom of HIDS is recurrent fever that appears already in infancy. Interestingly, IgD levels usually only increase during episodes of fever. Other symptoms include joint pain, enlarged lymph nodes, headaches, and abdominal pain.

  • Type E immunoglobulins (IgE)
  • Type G immunoglobulin (IgG)
  • The immune system - how does it work?
About the authorKarolina Karabin, MD, PhD, molecular biologist, laboratory diagnostician, Cambridge Diagnostics Polska A biologist by profession, specializing in microbiology, and a laboratory diagnostician with over 10 years of experience in laboratory work. A graduate of the College of Molecular Medicine and a member of the Polish Society of Human Genetics. Head of research grants at the Laboratory of Molecular Diagnostics at the Department of Hematology, Oncology and Internal Diseases of the Medical University of Warsaw. She defended the title of doctor of medical sciences in the field of medical biology at the 1st Faculty of Medicine of the Medical University of Warsaw. Author of many scientific and popular science works in the field of laboratory diagnostics, molecular biology and nutrition. On a daily basis, as a specialist in the field of laboratory diagnostics, he runs the content department at Cambridge Diagnostics Polska and cooperates with a team of nutritionists at the CD Dietary Clinic. He shares his practical knowledge on diagnostics and diet therapy of diseases with specialists at conferences, training sessions, and in magazines and websites. She is particularly interested in the influence of modern lifestyle on molecular processes in the body.

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Immune system