IgG Subclasses

Immunology

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Description

IgG1, IgG3 & IgG4 immunoglobulins are predominantly directed against protein antigens, while IgG2 antibodies are directed towards polysaccahride antigens. IgG1 is the major contributor to total IgG. It is important to note that normal total IgG and subclass IgG levels do not exclude significant humoral immunodeficiency. Individuals can have normal levels of immunoglobulins but still be unable to mount an adequate immune response to an invading pathogen. Patients can have low or absent IgG subclasses but normal total immunoglobulin concentrations [1]. Low IgG1 can be seen in primary or secondary immunodeficiency but often does not occur in isolation. Low IgG2 concentration may be observed in individuals susceptible to bacterial infections. The clinical significance of low/absent IgG3 and IgG4 is uncertain [2].

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Indications

Immunodeficiency. IgG4 related diseases.

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Sample Type

2mL Serum (Gel 5mL Yellow tube). Requests from outside Sheffield: Transport at ambient temperature via Royal Mail or Courier.

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Reference Range

Age | IgG1 | IgG2 | IgG3 | IgG4
Cord Blood |3.6 - 8.4 | 1.2 - 4.0 | 0.3 - 1.5 | <0.5|
6 months |1.5 - 3.0 | 0.3 - 0.5 | 0.1 - 0.6 | <0.5 |
2 years |2.3 - 5.8 | 0.3 - 3.9 | 0.1 - 0.8 | <0.5 |
5 years |2.3 - 6.4 | 0.7 - 4.5 | 0.1 - 1.1 | <0.8 |
10 years |3.6 - 7.3 | 1.4 - 4.5 | 0.3 - 1.1 | <1.0 |
15 years |3.8 - 7.73| 1.3 - 4.6 | 0.2 - 1.2 | <1.1 |
Adult |3.2 - 10.2| 1.2 - 6.6 | 0.2 - 1.9 | <1.3 |

Reference ranges established in house and PRU collaboration.

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Turnaround Time

Within 1 week

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Testing Frequency

Weekly

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External Notes

Discuss with Immunologist.

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References

Herriot R and Sewell WAC. Antibody deficiency. J. Clin. Pathol. 2008. 61(9):994-1000.PRU Handbook of Clinical Immunochemistry. 4th Ed. 2007.Buckley RH. Immunoglobulin G subclass deficiency: fact or fancy? 2002. Curr Allergy Asthma Rep. 2(5):356-360. [Ref 1]Maguire GA, Kumararatne DS, Joyce HJ. Are there any clinical indications for measuring IgG subclasses? 2002Ann Clin Biochem. 39(4):374-377. [Ref 2]

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See Also

Functional antibodies.

Please note: the above information is subject to change and we endeavour to keep this website up to date wherever necessary.