Immunoglobulins form a significant portion of humoral immunity. The most common antibody among all antibodies is IgG whose percentage sums up to an approximation of around 73-81 percent. It’s production is carried out by memory cells also referred as plasma cells and has two sites where specific antigens can attach to.
Being the most significant portion of serum antibodies, it aids in humoral immunity by enabling the body to protect itself from pathogenic microorganisms which causes infections. Its two antigen binding sites are helpful as it can form attachment to many virulent microorganisms for example fungi, parasites, bacteria and virusesand works towards ensuring that they are being cleared from the blood streams. These can result to inflammatory changes in the body such as redness, edema, pain, rising temperatures and loss of fiction which can be detected by fit ab’s food intolerance test To achieve all of its functions it employs various mechanism in its action that are listed below.
- IgG attaches to virulent microorganisms making them unable to circulate throughout the body: Bound pathogens clot together in a process called agglutination and are prepared for breakdown by phagocytic cells.
- IgG triggers classical pathway that is part of the body’s compliment system leading to a series of reactions that eliminate the pathogen.
- Neutralization of toxins produced by pathogens by IgG helps in fighting infections.
- In Proteolysis which is the breakdown of antigens that are protein in nature and initiated by cell cytotoxicity IgG plays a key role in destroying infected cells or any other abnormal cells including cancerous cells.
- It also works in hand with type two and three hypersensitivity reactions to clear all the pathogenic microorganisms and affected body cells.
- Because of its small size, it can penetrate the placenta and thus giving protection to the fetus in utero and neonate before its before its humoral immunity is fully established. . Thus it’s levels should always be maintained especially in pregnancy so
as the fetus can get the protection it requires.
- Antibodiesof IgG are big in size which are formed structurally by four chains of peptide molecules. It’s structure is composed of two classes of y chains which are known to have heaviness of about 50Dka and two other chains that are lighter weighing approximately 25DKa. In addition the heavy chains are connected to another heavy chains and lighter chains are also connected to the other which is also lighter and this leads to the shape formation of immunoglobulin G. The tips of the antibody have the antigen binding sites which are modifiable allow attachment to many antigens which are different. This characteristic is referred to as adaptability of the antibody. Modifications to these sites gives rise to four different types of IgG antibodies namely IgG 1 to IgG 4.
There are four subclasses of IgG named 1-4 based on their quantity levels that are within the blood and extracellular fluids. The subclasses have difference in their hinge structure which confers them adaptability to the type of antigen produced against.
IgG provide secondary immunity in that sensitization of the body against a specific pathogen is important in their production by memory B cells.
In the practice of medicine, IgG measurement levels are important in making diagnosis body’s immunity response to various virulent microorganisms present in the body. It can also be used to diagnose particular antibodies against certain conditions such as autoimmune hepatitis. Clinically measured IgG antibody indicate one’s immune status which is important for one to know so as to take protective measures.
In cases where one lacks IgG antibodies or they are present in low amount, infections are likely to occur due to the incapability of the body to provide itself with a defense mechanism. Such deficiencies are not age limited and therefore affects people of all ages. This deficiencies occur if the production of IgG is impaired and the impairment is caused due to various reasons such as nutritional deficiencies of proteins.
Deficiency of IgG manifests with the following infections:
- Respiratory infections and sinusitis e.g. pneumonia and bronchitis.
- Gastrointestinal infections such as gastritis.
- Ear infections e.g. otitis media.
- Sore throat infections e.g. laryngitis.