IgG

Definition

IgG, or Immunoglobulin G, is the most abundant type of antibody found in the bloodstream and extracellular fluid, playing a crucial role in the body's adaptive immune response. It is primarily responsible for identifying and neutralizing pathogens such as bacteria and viruses, as well as providing long-term immunity after infection or vaccination. IgG is unique because it can cross the placenta, offering passive immunity to the fetus.

5 Must Know Facts For Your Next Test

1. IgG accounts for approximately 75-80% of all antibodies in the serum, making it the most prevalent immunoglobulin in the body.
2. It has four subclasses (IgG1, IgG2, IgG3, IgG4), each with distinct functions and properties related to immune responses.
3. IgG is crucial for opsonization, a process where pathogens are marked for destruction by phagocytic cells.
4. It plays a significant role in complement activation, enhancing the ability of antibodies to eliminate pathogens.
5. The presence of IgG can be measured through serological tests to determine immunity against specific pathogens or infections.

Review Questions

• How does IgG contribute to the immune response against parasites?
  • IgG plays a vital role in the immune response against parasites by recognizing and binding to antigens present on their surface. This binding facilitates opsonization, which marks the parasites for destruction by immune cells like macrophages and neutrophils. Additionally, IgG can activate the complement system, further enhancing the body's ability to eliminate these pathogens. Its high affinity and specificity make IgG essential in controlling parasitic infections effectively.
• Discuss how the ability of IgG to cross the placenta impacts fetal immunity.
  • The ability of IgG to cross the placenta is critical because it allows for passive immunity transfer from the mother to the fetus during pregnancy. This transfer provides the developing fetus with antibodies that can protect against infections during the first few months of life when their immune system is still maturing. This passive immunity is essential for safeguarding newborns from various pathogens until they can produce their own antibodies through active immunization or infection.
• Evaluate the significance of measuring IgG levels in clinical settings for diagnosing and managing parasitic infections.
  • Measuring IgG levels in clinical settings is significant for diagnosing and managing parasitic infections because it provides insight into an individual's immune status. Elevated IgG levels indicate past exposure or active infection, helping healthcare providers determine appropriate treatment strategies. In addition, monitoring changes in IgG levels can inform the effectiveness of interventions or vaccinations. This evaluation is crucial for tailoring patient management plans and understanding individual responses to parasitic diseases.

Related terms

Antibody: A protein produced by B cells that binds to specific antigens on pathogens, marking them for destruction by the immune system.

B cells:

A type of white blood cell that produces antibodies and plays a key role in the adaptive immune response.

Passive Immunity: Immunity gained through the transfer of antibodies from another source, such as mother to fetus or through antibody injections.