IgG Full Form
What is the full form of IgG?
“Antibodies” refers to an “immunoglobulin” – a class of protein occurring in the serum and cells of the immune system, capable enough to form certain particular combinations with antigens generated in susceptible animals. Antibodies are largely generated as a response to the invasion of foreign molecules (referred to as "antigens") in the body. The antibodies are commonly denoted as immunoglobin, or Ig. The IgG (Immunoglobulin G) occurs to be the most abundant immunoglobulin in the human serum. In this article, we will look at the details of immunoglobulin G (IgG).
- What is the full form of IgG?
- Antibodies (Immunoglobulin)
- classes of Immunoglobulin
- Immunoglobulin G (IgG)
- Clinical significance of IgG
Antibodies (Immunoglobulin)
Antibodies generated in the response to the antigen encountered in the body, are majorly glycoproteins, i.e., 82-96% protein and 4-18% carbohydrates, that form humoral immunity. The antibodies (immunoglobulins) occur as a Y-shaped unit, of four polypeptide chains. The Y structure comprises two identical copies of heavy chain and light chain, named depending upon their molecular weight. Likewise, the Y structure is composed of two antigen-specific arms and a tail. The arms are variable but specific to the antigen and bind with the antigen, while the tail remains constant and binds to immune cells.
classes of Immunoglobulin
The immunoglobulins are classified into five classes: IgG, IgD, IgA, IgM, and IgE. Heavy chains of IgG, IgM, IgA, IgD, and IgE, are known as γ, δ, α, μ and ε, respectively. The heavy chains of IgG and IgA comprise approximately 450 amino acids, while that of IgM and IgE is approximately 550 amino acids. These subclasses of antibodies differ in the numbers of disulphide bonds and the hinge region in the basic structure of the immunoglobulin.
Immunoglobulin G (IgG)
Immunoglobulin G occurs abundantly in the human serum. It occurs in monomeric forms. The four subclasses of IgG included IgG1, IgG2, IgG3 and IgG4. These subclasses are named after their abundance in the serum, where IgG1 is the most widely found IgG. The IgG1 occurs to be majorly responsible for inducing the thymus-mediated response against proteins and polypeptide antigens. Likewise, it occurs to be involved in opsonization and stimulation of complement cascade. The IgG2 induces the immune response against carbohydrate and polysaccharide antigens. Equally, IgG3 plays a vital role in invading proteins or polypeptide antigens. However, the role of IgG4 still remains unknown but was found to be abundantly present in the patient suffering from autoimmune pancreatitis, swelling of the bile duct, and scarring of lung tissues.
Clinical significance of IgG
A deficiency of IgG could lead to several disorders and infections. The patient mostly suffers from a sinus infection, gastrointestinal infection, respiratory infection (bronchitis, pneumonia), sore throat, and several other life-threatening infections. The low levels of IgG could be potentially treated by the intravenous administration of IgG within 3-4 weeks with the stipulated doses.
Other Related Full Forms
Frequently Asked Questions (FAQs)
Generally, a blood test could be made to detect the deficiency of IgG. However, even the saliva and cerebrospinal fluid could be used to detect the deficiency of IgG.
Hypogammaglobulinemia and reoccurring respiratory infections (generally in infants) are majorly associated with the deficiency of IgG1 and IgG2, respectively.
The normal levels of IgG in individuals (0-15 years) occur between 500-1610 mg/dL, while in individuals over 16 years, they are between 600-1600 mg/dL.
IgG3 and IgG4 form approximately 5–10% and less than 4% of the total IgG in the serum, respectively.
Foods with high contents of vitamin A, vitamin E, lycopene, and zinc improve the levels of immunoglobin in the body. Food items such as eggs, cream, red meat, cheese, beans, cashews, green leafy vegetables, avocados, apricots, watermelon, etc. provide a sufficient amount of the mentioned nutrients.