Immunoglobulins/ antibodies are molecules made by the white blood cells that defend the system against infections and cancer. The main function of immunoglobulins is to bind to foreign invaders like viruses and bacteria, thus neutralizing the foreign cells and sending signals to white blood cells to destroy them.

There are five types of immunoglobulins. When the levels are higher or lower than normal it indicates a sign of underlying health conditions.
immunoglobulins blood test

For instance, myeloma cancer is often linked with high levels of immunoglobulins and at times kidney disease can cause low levels. The healthcare provider treats low immunoglobulin levels with an intravenous (IV) immunoglobulin infusion.

Read on to learn more about immunoglobulins, how immunoglobulins help defend the body against infection, and tests used to measure levels of immunoglobulins.

What Are Immunoglobulins?

Immunoglobulins are Y-shaped molecules that are made up of sugar and protein made by plasma cells, a type of white blood cell. Their primary functions include:

  • Averting foreign invaders from entering the cells by neutralizing them
  • Marking foreign invaders and destroying them by white blood cells called macrophages
  • Stimulating damage of foreign invaders by triggering other immune responses

Immunoglobulins contain a highly variable part called paratope, which binds to sections of foreign molecules called epitopes like lock and key.

The paratope comprises a highly variable part that permits the body to produce millions of types of antibodies. Each antibody only binds with one foreign molecule.

What Are Plasma Cells?

Plasma cells are triggered by B cells, which can make huge quantities of immunoglobulins that are programmed to identify a particular epitope.

The blood comprises three types of blood cells:

  • Red blood cells - carry oxygen throughout the body
  • Platelets that help blood clot after an injury or accident
  • White blood cells safeguard the body from foreign invaders and cancers

The blood cells are derived from special cells called hematopoietic stem cells found in the bone marrow. These cells can form two other types of cells called myeloid stem cells or lymphoid stem cells. Further lymphoid stem cells can become three types of white blood cells that play a crucial role in adaptive immunity:

  • Natural killer cells: Have special enzymes to destroy cancer cells or viruses
  • T cells: Damage infected cells and activate other immune cells
  • B cells: Convert to plasma cells when triggered by foreign invaders and produce Immunoglobulins

Classes/Types Of Immunoglobulins

Immunoglobulins are made up of two molecules called light chains and two heavy chains. Five types are found in the human body and each of them is named after the type of heavy chain they contain:

IgM: Provides quick defense against infectious diseases.

IgG: Offers most of the immunoglobin-based immunity against foreign molecules but slower effect than IgG.

IgA: Offers protection against infectious agents and is found mostly in mucus membranes. It shields the surfaces of the respiratory, digestive, and urinary systems.

IgE: Proffers safety against parasites. It also triggers histamine release from white blood cells called mast cells and basophils to activate allergic reactions.

IgD: Function is unknown.

How Do Immunoglobulins Help In The Diagnosis Of A Health Condition?

Immunoglobulin levels are a helpful biomarker for assessing several disease conditions, including immunodeficiencies, and autoimmune disorders. Your healthcare provider may suggest testing immunoglobulin levels if immunodeficiency runs in the family or if a person exhibits symptoms of a condition linked to atypical immunoglobulin levels such as sudden weight loss or continuous diarrhoea.

Also Read: Multiple Myeloma: Causes, Symptoms And Treatment

Low Immunoglobulin Levels

Low immunoglobulin levels indicate that your immune system is not working well. Health problems linked to low immunoglobulin levels include:

  • Severe infections
  • Side effects of medications
  • Kidney problem
  • Burns
  • Malnutrition

Generally, a few people are born with a lower-than-normal immunoglobulin level.

High Immunoglobulin Levels

Elevated immunoglobulin levels are observed in health conditions such as:

  • Autoimmune Disease
  • Hepatitis
  • Cirrhosis
  • Chronic infection
  • Some cancers like multiple myeloma
  • Allergies
  • Inflammatory bowel disease

Antibody Deficiency Disorders

Some people do not make immunoglobulins or do not produce as sufficient as they should be, and these conditions are called antibody deficiency disorders. This may be seen shortly after birth with recurrent infection. These conditions are mostly treated with intravenous immune globulin (IVIG).

While some people may have autoimmune conditions where they produce immunoglobulins against their own cells, and it occurs through a process called molecular mimicry. IVIG is often used to treat these conditions.

Also Read: Lymphocytopenia: Causes, Symptoms And Treatment

Immunoglobulin Blood Tests Results

Healthcare providers often recommend testing circulating levels of IgA, IgG, and IgM to determine immune function.

The immunoglobulin tests results indicate:

IgA Test

Approximate Values: 0.8 to 3.0g/L

Health conditions associated with a low score include:

  • Kidney damage
  • Digestive problems
  • Ataxia-telangiectasia
  • Low or lack of IgA -congenital
  • Leukemia

Health conditions linked with a high score:

  • Monoclonal gammopathy of unknown significance (MGUS)
  • Multiple myeloma
  • Rheumatoid arthritis
  • Cirrhosis

IgD Test

Approximate Values: 0.003 to 0.03g/L

Health Disorders linked with a low level indicate: Studies are still ongoing to understand the nature and significance of low IgD.

Conditions associated with High score: In very rare cases myeloma.

IgE Test

Approximate Value: 0.0002 to 0.002g/L       

Health issues associated with low levels:

  • A rare condition called ataxia-telangiectasia

Health problems associated with a high score:

  • Parasitic infection
  • Allergic reactions
  • Asthma
  • Atopic dermatitis
  • Some types of cancer
  • Certain types of autoimmune diseases
  • Rarely multiple myeloma

IgG test     

Approximate Value: 6.0 to 16.0g/L

Health problems associated with low scores:

  • Waldenstrom’s macroglobulinemia
  • Leukemia
  • Kidney damage
  • Rarely, people are born without IgG immunoglobulin

Health conditions linked with a high score:

  • AIDS
  • MGUS
  • Multiple myeloma
  • Chronic hepatitis, multiple sclerosis

IgM Test

Approximate Value: 0.4 to 2.5g/L

Health disorders linked with low scores:

  • Multiple myeloma
  • Leukemia

Health issues associated with a high score:

  • Waldenstrom’s macroglobulinemia
  • Early viral hepatitis
  • Mononucleosis
  • Rheumatoid arthritis
  • Kidney damage
  • Parasitic infection

Thyroid-Stimulating Immunoglobulin (TSI) Hormone

Approximate Value: Under 0.54 IU/L   

Health conditions with a high score: TSI is a type of IgG that results in the thyroid gland releasing more thyroid hormones. Higher than normal levels may indicate Graves’ disease.