Isotypes of immunoglobulins

Kinashi, T., Godal, T., Noma, Y., Ling, N.R., Yaoita, Y., Honjo, T. (1987). Human neoplastic B cells express more than two isotypes of immunoglobulins without deletion of heavy-chain constant-region genes. Genes Dev. 1, 465-470. 

The basic structure of all immunoglobulin (Ig) molecules comprises two identical light chains and two identical heavy chains linked together by disulfide bonds (Figure IS.2a). There are two different classes, or isotypes, of light chains, X and k, but there is no known functional distinction between them. Heavy chains, by contrast, have five different isotypes that divide the immunoglobulins into different functional classes IgG, IgM, IgA, IgD, and IgE, each with different effector properties in the elimination of antigen... 

Five major sub-classes of immunoglobulin (isotypes) (Table 7.1) have... 

Ischemia. Deficiency of blood in a part, usually results from functional constriction or actual obstruction of a blood vessel. Isotype. An immunoglobulin heavy- or light-chain class or subclass characterized... 

Liu, Y.J., Malisan, F., de Bouteiller, O., Guret, C., Lebecque, S., Banchereau, J., Mills, F.C., Max, E.E., Martinez-Valdez, H. (1996). Within germinal centers, isotype switching of immunoglobulin genes occurs after the onset of somatic mutation. Immunity 4,241-250. 

B cells recognize native or denatured forms of proteins or carbohydrates in soluble, particulate, or cell-bound form. Activated B cells differentiate into plasma cells and produce antibodies, soluble proteins known as immunoglobulins (Ig), that circulate freely and react specifically with the invoking antigen. There are several classes (called isotypes) of Ig molecules—IgM, IgG, IgA, IgE, and IgD. IgM is the predominant antibody in the primary immune response (following initial exposure to an antigen). IgG usually appears later, following a primary infection, but is the predominant antibody... 

As to cryoglobulins, both type I (single component or 1 isotype or subclass of immunoglobulin, or, rarely, a monoclonal light chain) and type II (mixed cryoglobulins with monoclonal IgM as antibody and IgG as antigen) may be present. Nearly 10% of all WM molecules are cryoprecipitable (Kl). Infiltration of bone marrow by tumor cells can result in severe anemia. 

Brenner MK, Wimperis JZ, Reittie JE, Patterson J, Asherson GL, Hoffbrand AV, Prentice HG. Recovery of immunoglobulin isotypes following T cell depleted allogeneic bone marrow transplantation. Br J Haematol 1986 64(l) 125-32. 

Hassner, A., Lau, M. S., Goetzl, E. J., and Adelman, D. C. (1993). Isotype-specific regulation of human lymphocyte production of immunoglobulins by sustained exposure to vasoactive intestinal peptide. J. Allergy Clin. Immunol. 92, 891-901. 

Snow RE, Djukanovic R, Stevenson FK Analysis of immunoglobulin E VH transcripts in a bronchial biopsy of an asthmatic patients confirms bias towards VH5, and indicates local clonal expansion, somatic mutation and isotype switch events. Immunology 1999 98 646-651. 

Many different immunoassays can be used for the quantification of immunoglobulin isotypes and subclasses, varying from ELISA/ FEIA and radial immunodiffusion (RID) to nephelometry/turbid-imetry (Rose et al., 2002). The immunoglobulin isotypes IgA, IgG, and IgM in particular are present in relatively high concentrations in the circulation (0.5-20 g/l). These isotypes are often quantified by... 

Fc receptors. Receptors expressed on a wide range of cells, interacting with the Fc portion of immunoglobulins belonging to various isotypes. Membrane-bound Fc receptors mediate different effector functions (endocytosis, antibody-dependent cell-mediated cytotoxicity) and induce mediator release. Both the membrane-bound and soluble forms of Fc receptors regulate antibody production of B cells. 

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