Immune response immunoglobulin classes

The members of the immunoglobulin superfamily that are encoded in the major histocompatibility complex (MHC) (Fig. 8) constitute a large family which, on the basis of functional criteria, can be divided into two major sets [88—91]. The first consists of antigen-presenting molecules and includes the classical transplantation antigens (class I, see below) and immune response factors (class II). The function of the second is presumably in differentiation, since these molecules (which in the mouse include the Qa and TL antigens [92]) are expressed on specific cell types molecules analogous to this second set V (CD1) are also encoded by a small family... 

Type I allergic reactions are inappropriate immune responses to an allergen with preferential synthesis of immunoglobulin E (IgE), a special antibody class, which binds to mast cells and basophilic granulocytes via Fee receptors. Binding of the allergen to the cell-bound IgE initiates the rapid release of allergic mediators, most prominently histamine, and the de novo synthesis of arachidonic acid metabolites and cytokines, which are responsible for the clinical symptoms. 

Immunoglobulin. Immunoprotein glycoprotein of animal origin with known antibody activity, or protein related by chemical structure, which may or may not have antibody activity. Divided into five classes IgM, IgG, IgA, IgD, and IgE on the basis of structure and biological activity. Immunostimulant. Stimulating various functions or activities of the immune system. Immunosuppressant. An agent capable of suppressing immune responses. 

Antibodies are molecules secreted by terminally differentiated B cells (a type of lymphocyte) known as plasma cells. Nearly all rabbit primary antibodies and most mouse monoclonal antibodies are immunoglobulins (Igs). There are five classes of Igs that differ structurally and functionally. Immunoglobulin G (IgG) molecules are the major class of Igs in the blood, which are predominantly produced in the secondary immune response. 

McMenamin C, Holt PG The natural immune response to inhaled soluble protein antigens involves major histocompatibility complex (MHC) class I-restricted CD8+ T cell-mediated but MHC class Il-restricted CD4+ T cell-dependent immune deviation resulting in selective suppression of immunoglobulin E production. J Exp Med 1993 178 889-899. 

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... 

Although the cellular and humoral response in experimental animals tends to be relatively uniform, it must be remembered that in man (and domestic animals) the immune responses can vary enormously. This is undoubtedly related to human genetic diversity - unlike the uniform genetic background of most experimental animals. These responses have been much studied in hydatid disease and (T. solium) cysticercosis. In the latter case, the frequency of different precipitation bands in serum immuno-electrophoresis (Fig. 11.8) and of the immunoglobulin classes (Table 11.4) show great variation between patients (226). Moreover, some patients show no humoral or cellular response whatsoever (226). Similarly, there is much variation in the immune responses to hydatid disease and, again, some patients show no detectable antibody (734). 

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