Difference between IgG and IgM Antibodies

IgG (Immunoglobulin G) and IgM (Immunoglobulin M) are types of antibodies produced by the immune system. IgG is the most abundant antibody, providing long-term immunity against pathogens, while IgM is the first antibody produced in response to an infection, providing initial defines. Both play crucial roles in the body’s immune response to protect against diseases. This article on Difference between IgG and IgM explores the similarities and differences between these two classes of antibodies.

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Difference between IgG and IgM

Learn more: Immunoglobulins: Structure and Functions

CharacteristicIgG AntibodiesIgM Antibodies
Number of Antigen Binding Sites2 (one for each monomer)10 (2 binding sites per monomer)
SizeSmaller, about 150 kDaLarger, about 900 kDa
Half-LifeLonger half-life (weeks to months)Shorter half-life (days)
Timing of ProductionProduced during secondary immune responsesProduced during primary immune responses
Maternal TransferCrosses the placenta, conferring passive immunity to the foetusDoes not cross the placenta
Tissue DistributionFound in extracellular fluids and tissuesPredominantly in blood circulation
Effector FunctionsOpsonization, complement activation, neutralization, antibody-dependent cellular cytotoxicity (ADCC), and neonatal immunityComplement activation and agglutination of microbes
Role in Immune ResponseProvides long-term immunity and memory to subsequent infectionsEarly responder to infections, signals ongoing immune response
Presence in Early Immune ResponseProduced later in the immune responseProduced early in the immune response
Maturation of AffinityUndergoes affinity maturation in secondary immune responsesAffinity maturation less prominent
Immunoglobulin TypeMost abundant immunoglobulin class in serumFirst antibody class produced during an immune response
AgglutinationLess efficient at agglutination of antigensEfficient at agglutinating microbes
Diagnostic SignificanceUsed in diagnosing chronic infections, autoimmune diseases, and allergiesUsed as a marker for recent infections or initial response
Autoimmune ReactionsCan contribute to autoimmune reactionsCan contribute to autoimmune reactions
Rheumatoid FactorCan form immune complexes with rheumatoid factorOften detected in autoimmune disorders and infections

Difference between IgG and IgM

Similarities between IgG and IGM

Ø  Both IgG and IgM antibodies are crucial components of the immune system and play roles in neutralizing pathogens, such as bacteria and viruses.

Ø  Both IgG and IgM antibodies are produced by B cells in response to foreign invaders like pathogens.

Ø  Both IgG and IgM antibodies have a Y-shaped structure composed of four protein chains, including two heavy chains and two light chains.

Ø  IgG and IgM can contribute to immunological memory, meaning they provide protection against the same pathogen if encountered again in the future.

Ø  Both antibodies can activate the complement system.

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