IgG and IgE explained
By Lauren Amphlett

Immunoglobulins, also known as antibodies, are proteins produced by the immune system in response to the presence of foreign substances, such as viruses and bacteria. There are different types of immunoglobulins, including IgG and IgE, which play different roles in the immune system. In aspergillosis, both IgG and IgE antibodies play important roles in the immune response to the Aspergillus fungus. This post aims to provide important information about the differences between IgG and IgE.

What is IgG?

IgG is the most common type of immunoglobulin in the bloodstream, accounting for about 75% of all antibodies in the body. IgG plays an important role in fighting off bacterial and viral infections and is also involved in the immune response to certain types of cancer cells. IgG can cross the placenta and provide protection to a developing foetus, which is why it is referred to as a “maternal antibody.”

Elevated levels of IgG antibodies to Aspergillus are often seen in individuals with Chronic Pulmonary Aspergillosis (CPA), and measuring IgG antibody levels is an important diagnostic tool for the condition.

What is IgE?

IgE is a type of immunoglobulin that plays a role in the allergic response. IgE is produced in response to exposure to allergens, such as pollen, pet hair, and certain food, and for patients with allergic bronchopulmonary aspergillosis – aspergillus fungus. When IgE binds to an allergen, it triggers the release of histamine and other chemicals, leading to the symptoms of an allergic reaction, such as:

  • Wheezing
  • Coughing
  • Shortness of breath
  • Chest pain or tightness

Differences between IgG and IgE

There are several differences between IgG and IgE, including:

  • IgG plays a role in fighting off bacterial and viral infections, while IgE is involved in the allergic response.
  • IgG has a longer half-life in the bloodstream than IgE, which means it stays in the body longer.
  • IgG takes longer to produce in response to an infection or exposure to an antigen, while IgE is produced rapidly in response to an allergen.

Both IgG and IgE antibodies play important roles in the immune response in aspergillosis. While IgG helps to neutralise and eliminate the fungus, IgE triggers the allergic response and leads to symptoms in individuals with Allergic Bronchopulmonary Aspergillosis (ABPA). Measuring antibody levels to Aspergillus can be helpful in diagnosing and monitoring these conditions.

More information on the role of IgE and IgG can be found via the links below:

https://onlinelibrary.wiley.com/doi/10.1111/all.14908

https://www.britannica.com/science/immune-system/Classes-of-immunoglobulins

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