General Information of HIF (ID: HIFM0278)
HIF Name	Immunoglobulin G4
HIF Synonym(s)	IgG4
HIF Classification	Immunoglobulin (Ig)
Description	Immunoglobulin G4(IgG4) , the least represented human IgG subclass in serum, is an intriguing antibody with unique biological properties, such as the ability to undergo Fab-arm exchange and limit immune complex formation. IgG4 plays a protective role in allergy by acting as a blocking antibody, and inhibiting mast cell degranulation, but a deleterious role in malignant melanoma, by impeding IgG1-mediated anti-tumor immunity.				[1]

Microbe Species (MIC) Regulated by This HIF
Capnocytophaga ochracea (CFB bacteria)			MIC00328
Description	The activity of proteolytic enzymes from Capnocytophaga ochracea could effect enzymolysis of human immunoglobulin G4(lgG4).				[2]
Clonorchis sinensis (firmicutes)			MIC01834
Description	The intensity of Clonorchis sinensis infection is associated with the positive rate of IgG4.				[3]
Erysipelothrix rhusiopathiae (firmicutes)			MIC00559
Description	IgG4 is associated with the abundance of Erysipelothrix.				[4]
Helicobacter pylori (epsilon-proteobacteria)			MIC00669
Description	IgG4 is associated with the abundance of Helicobacter pylori.				[5]
Mycobacterium tuberculosis (actinobacteria)			MIC00857
Description	Mycobacterium tuberculosis may be associated with IgG4-related disease.				[6]
Porphyromonas gingivalis (CFB bacteria)			MIC01000
Description	The activity of proteolytic enzymes from Porphyromonas gingivalis could effect enzymolysis of human immunoglobulin G4(lgG4).				[2]
Saccharomyces cerevisiae (budding yeasts)			MIC01145
Description	IgG4 is associated with Saccharomyces cerevisiae.				[7]
Staphylococcus aureus (firmicutes)			MIC01208
Description	Persistent Staphylococcus aureus carriers trend toward IgG4 responses to a larger number of antigens than persistent noncarriers.				[8]
Streptococcus sp. (firmicutes)			MIC01276
Description	IgG4 is associated with the abundance of Streptococcaceae.				[4]

References
1	Human IgG4: a structural perspective.Immunol Rev. 2015 Nov;268(1):139-59. doi: 10.1111/imr.12349.
2	Immunoglobulin-degrading enzymes in localized juvenile periodontitis.J Periodontal Res. 1992 May;27(3):176-83. doi: 10.1111/j.1600-0765.1992.tb01666.x.
3	Usefulness of IgG4 subclass antibodies for diagnosis of human clonorchiasis.Korean J Parasitol. 1999 Dec;37(4):243-8. doi: 10.3347/kjp.1999.37.4.243.
4	IgGs containing - and -type light chains and of all subclasses (IgG1-IgG4) from the sera of patients with autoimmune diseases and viral and bacterial infections hydrolyze DNA.J Mol Recognit. 2012 Jul;25(7):383-92. doi: 10.1002/jmr.2185.
5	[Abnormal immunity in IgG4-related autoimmune pancreatitis].Nihon Rinsho Meneki Gakkai Kaishi. 2014;37(1):11-8. doi: 10.2177/jsci.37.11.
6	Broadening the Differential Diagnosis of IgG4-Related Pleuritis.Am J Med Sci. 2019 Jan;357(1):81-82. doi: 10.1016/j.amjms.2018.08.003. Epub 2018 Aug 6.
7	Anti-food and anti-microbial IgG subclass antibodies in inflammatory bowel disease.Scand J Gastroenterol. 2016 Dec;51(12):1453-1461. doi: 10.1080/00365521.2016.1205130. Epub 2016 Jul 25.
8	IgG4 subclass-specific responses to Staphylococcus aureus antigens shed new light on host-pathogen interaction.Infect Immun. 2015 Feb;83(2):492-501. doi: 10.1128/IAI.02286-14. Epub 2014 Nov 17.

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