Immunoglobulin G

Immunoglobulin G (IgG) represents one of the five main classes of immunoglobulins, a group of proteins in the body that play a critical role in the immune response. IgG is particularly vital in our body's defense against bacterial pathogens<ref>

Immunoglobulin G: structure and functional implications of different subclass modifications in initiation and resolution of allergy(link). National Institutes of Health.

Accessed 2023-06-21.

</ref>.

Structure and Function

The IgG molecule is typically Y-shaped and composed of two heavy chains and two light chains. The variable regions at the ends of the 'Y' shape allow for specific binding to antigens<ref>

Structure and Function of the Immune System in the Spleen(link). National Institutes of Health.

Accessed 2023-06-21.

</ref>.

Its primary function is to bind to the specific antigens that triggered its production and render them for destruction. IgG is also able to cross the placenta, providing a temporary immune defense to newborns.

Subclasses and Variability

There are four subclasses of IgG in humans, named IgG1, IgG2, IgG3, and IgG4, with distinct roles and properties. Some are better at activating complement, while others are more effective at binding to specific types of antigens or activating immune cells<ref>

IgG subclass switching and clonal expansion in cutaneous melanoma and normal skin(link). National Institutes of Health.

Accessed 2023-06-21.

</ref>.

Clinical Significance

The level and type of IgG antibodies in a patient's blood can provide diagnostic information about immune status, infections, and autoimmune diseases. Deficiencies in IgG production or function can lead to recurrent infections and are often treated with immunoglobulin replacement therapies<ref>

Primary Immunodeficiency Diseases: An Update on the Classification from the International Union of Immunological Societies Expert Committee for Primary Immunodeficiency(link). National Institutes of Health.

Accessed 2023-06-21.

</ref>.

References

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Immunoglobulin_G

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  Surface structure of an IgG1 antibody
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  Anatomy of an IgG antibody
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