The Key Role of IgG in Immune Response and Protection Against Pathogens

Immunoglobulins that are most abundant and are responsible for resistance against many viruses, bacteria, and bacterial toxins areA) IgA.B) IgD.C) IgE.D) IgG.E) IgM.

The correct answer is D) IgG

The correct answer is D) IgG.

IgG (Immunoglobulin G) is an immunoglobulin that is most abundant in the bloodstream and represents about 75-80% of all the immunoglobulins in the body. It is produced by plasma cells primarily in response to viral and bacterial infections.

IgG plays a crucial role in the immune system’s ability to neutralize and eliminate pathogens such as viruses, bacteria, and bacterial toxins. It acts by binding to the surface of the pathogens and signaling other components of the immune system to attack and eliminate them.

One of the significant functions of IgG is its ability to enhance the phagocytosis process. Phagocytic cells, such as neutrophils and macrophages, have receptors that bind to the constant region of IgG antibodies, a process called opsonization. Opsonized pathogens are then recognized and engulfed more efficiently by these phagocytic cells, leading to their destruction.

IgG also activates the complement system, a group of proteins that further enhance the immune response against pathogens. The binding of IgG to the surface of pathogens can initiate the classical pathway of the complement system, resulting in the formation of membrane attack complexes that destroy the pathogen’s cell membrane.

Furthermore, IgG is the only immunoglobulin that can cross the placenta from a pregnant mother to her fetus, providing passive immunity to the newborn during the early stages of life. This imparted immunity helps protect the baby against various infections until its own immune system matures.

In summary, IgG is the most abundant immunoglobulin in the body and plays a critical role in providing resistance against many viruses, bacteria, and bacterial toxins. It enhances phagocytosis, activates the complement system, and is responsible for passive immunity in newborns through the placenta.

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