Antibody Fc: Chapter 9. Human IgG Subclasses

Antibody Fc: Chapter 9. Human IgG Subclasses
ISBN-10
0128060301
ISBN-13
9780128060308
Series
Antibody Fc
Category
Medical
Pages
358
Language
English
Published
2013-08-06
Publisher
Elsevier Inc. Chapters
Authors
Theo Rispens, Gestur Vidarsson

Description

Immunoglobulins are a group of closely related glycoproteins composed of 82 to 96% protein and 4 to 18% carbohydrate. In humans, there are five classes of immunoglobulins, which differ in heavy-chain structure. Immunoglobulin G (IgG) is the major class of immunoglobulins in blood and can be further subdivided in subclasses. The four subclasses of IgG were discovered in the 1960s following extensive studies using specific rabbit antisera against human IgG myeloma proteins.1 They are designated IgG1, IgG2, IgG3, and IgG4, in order of decreasing abundance. Several decades of research has revealed subtle but profound differences among the subclasses. Each subclass has a unique profile with respect to antigen binding, immune complex formation, complement activation, triggering of effector cells, and placental transport (Table 9.1). In addition, IgG antibody responses to different types of antigens or pathogens often lead to marked skewing toward one of the subclasses. On the other hand, selective subclass deficiencies are usually not detrimental to the individual but do sometimes lead to enhanced susceptibility toward specific classes of pathogens. All in all, the acquired variability within the Ig locus seems to have been selected for beneficial changes during evolution for optimizing or fine-tuning the antibody-mediated immune response.

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