General Features Concerning Immunoglobulins

Extensive reviews have been written on the structure of immunoglobulins (Ig s).4,5 For understanding of the present article, a brief description of immunoglobulin structure is essential. 

There are five classes of immunoglobulins that can be distinguished by antigenic determinants on the heavy chains (see later), namely, IgM, IgG, IgA, IgD, and IgE. Antibody activity has been demonstrated in each of the classes. The molecular organization of immunoglobulins is based on a four-chain, unitary structure con- 

Some immunoglobulin molecules are functionally completed in four-chain, monomeric units (the IgG, IgD, and IgE classes). Others are formed into various sized polymers of this four-chain unit. The mammalian IgM molecules are pentamers having five units joined together by disulfide linkages. Mammalian IgA molecules are com- 

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