Antibody Classes


Antibodies are glycoproteins belonging to the immunoglobulin family. The immunoglobulins have a common four‐chain structure (two identical light chains and two identical heavy chains) and they can be divided into different classes (and subclasses) according to the isotype of the heavy chain. The heavy chain isotype will confer different structural and functional properties on each antibody class, so that each isotype will occupy a specific site in the body and have a specific role to play in the immune system.

Keywords: immunoglobulin classes; immunoglobulin subclasses; immunoglobulin structure; immunoglobulin function; immunoglobulin physico‐chemical properties

Figure 1.

Structure of the basic four‐chain unit of a human antibody molecule: (a) schematic structure and (b) spacefill model of the crystal structure of an intact human IgG1 (PDB code 1IGY).

Figure 2.

Polypeptide chain structures of the human antibody classes and subclasses: (a) IgG subclasses; (b) IgA subclasses, dimeric IgA and secretory IgA; (c) IgM; (d) IgE and (e) IgD.



Blattner FR and Tucker PW (1984) The molecular biology of immunoglobulin D. Nature 307: 417–422.

Burton DR and Woof J (1992) Human antibody effector functions. Advances in Immunology 51: 1–84.

Burton DR, Gregory L and Jefferis R (1986) Aspects of the molecular structure of IgG subclasses. In: Shakib F (ed.) Basic and Clinical Aspects of IgG Subclasses, pp. 7–35. Basel: Karger.

Corper AL, Sohi M, Bonagura VR et al. (1997) Structure of IgM rheumatoid factor Fab bound to its autoantigen IgG Fc reveals a novel topology of antibody–antigen interaction. Nature Structural Biology 4(5): 374–381.

Davis AC and Shulman MJ (1989) IgM – molecular requirements for its assembly and function. Immunology Today 10: 118–128.

Herr AB, Ballister ER and Bjorkman PJ (2003) Insights into IgA‐mediated immune responses from the crystal structures of human FcαRI and its complex with IgA1‐Fc. Nature 423: 614–620.

Jefferis R (1992) Antibody subclasses. In: Regenmortel MHV (ed.) The Structure of Antigens, pp. 321–338. London: CRC Press.

Kolar GR and Capra JD (2003) Immunoglobulins, structure and function. In: Paul WE (ed.) Fundamental Immunology, 5th edn, pp. 47–68. New York: Raven Press.

Krapp SY, Mimura Y, Jefferis R, Huber R and Sondermann P (2003) Structural analysis of human IgG‐Fc glycoforms reveals a correlation between glycosylation and structural integrity. Journal of Molecular Biology 325: 979–989.

Mestecky J and Russel WR (1986) IgA subclasses. Monographs in Allergy 19: 277–301.

Ollmann Saphire E, Stanfield RL, Crispin MDM et al. (2002) Contrasting IgG structures reveal extreme assymetry and flexibility. Journal of Molecular Biology 319: 9–18.

Padlan E (1994) Anatomy of the antibody molecule. Molecular Immunology 31: 169–217.

Preud'homme J‐L, Petit I, Barra A et al. (2000) Structural and functional properties of membrane and secreted IgD. Molecular Immunology 37: 871–887.

Randall TD, Brewer JW and Corley RB (1992) Direct evidence that J chain regulates the polymeric structure of IgM in antibody‐secreting B cells. Journal of Biological Chemistry 267: 18002–18007.

Reth M (1992) Antigen receptors on B‐lymphocytes. Annual Review of Immunology 10: 97–121.

Rudd PM and Dwek R (1997) Glycosylation: heterogeneity and the 3D structure of proteins. Critical Reviews in Biochemistry and Molecular Biology 32: 1–100.

Sutton BJ and Gould HJ (1993) The human IgE network. Nature 366: 421–428.

Vladutiu AO (2000) Immunoglobulin D: properties, measurement and clinical relevance. Clinical and Diagnostic Laboratory Immunology 7: 131–140.

Volkov VV, Kayushina RL, Lapuk VA et al. (2003) Solution structures of human immunoglobulins IgG and IgM and rheumatoid factor IgM‐RF. Crystallography Reports 48(1): 103–110.

Wan T, Beavil RL, Fabiane SM et al. (2002) The crystal structure of IgE Fc reveals an assymetrical bent conformation. Nature Immunology 3(7): 681–686.

Further Reading

Dwek RA, Lellouch C and Wormald MR (1995) Glycobiology: the function of sugar in the IgG molecule. Journal of Anatomy 187: 279–292.

Van Egmond M, Damen CA, van Spriel AB et al. (2001) IgA and the IgA Fc receptor. Trends in Immunology 22: 205–211.

Harris LJ, Larson SB, Hasel KW and McPhersson A (1997) Refined structure of an intact IgG2a monoclonal antibody. Biochemistry 36: 1581–1597.

Hexham JM, Carayannopoulos J and Capra DJ (1997) Structure and function in IgA. In: Shakib F (ed.) Antibody Engineering, pp. 72–87. Basel: Karger.

Janeway C, Travers P, Walport M and Shlomchik M (2001) Immune Biology: The Immune System in Health and Disease. New York: Garland Publishing.

Mestecky J and Russel MW (1997) Immunoglobulins and mechanism of mucosal immunity. Biochemical Society Transactions 25: 457–462.

Metzger H (1970) Structure and function of IgM macroglobulins. Advances in Immunology 12: 57–116.

Mudde GC, Hansel TT, Reijsen FC, Osterhoff BF and Bruijneel‐Koomen CAFM (1990) IgE: an immunoglobulin specialized in antigen capture? Immunology Today 11: 440–443.

Shakib F (ed.) (1990) The Human IgG Subclasses: Molecular Analysis of Structure, Function and Regulation. Oxford: Pergamon Press.

Steward MW (1984) Antibodies: Their Structure and Function. Outline Studies in Biology Series. London: Chapman & Hall.

Thorbecke JG and Leslie GA (1982) Immunoglobulin D: structure and function. Proceedings of the National Academy of Sciences of the USA 399: 1–410.

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Wingren, Christer, Alkner, Ulf, and Hansson, Ulla‐Britt(Sep 2005) Antibody Classes. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1038/npg.els.0003985]