Allotypic Markers

Allotypic markers for human yl. y2, y3, a2 and e heavy chains have been defined as Glm, G2m, G3m, A2m and Em (WHO meeting, 1976 [172]). The subclass heavy chain allotypes Glm, G2m, G3m and A2m are normally inherited in specific combinations. Lefranc et al. (1979) [173] determined five major and four minor Gm-Am haplotypes in Tunisians and found different common haplotypes in Caucasoids and Negroids. Protein sequence comparisons demonstrate that there are only two amino acid differences between the G3m (b) and G3m (a) allotypes [155], Restriction length polymorphism has been found for the Ca2 gene [174] thus, independent identification of the A2m allelomorphs, which were previously distinguishable only by serology, has been established. 

W.H.O. Review of the notation for the allotypic and related markers of human immunoglobulins. W.H.O. Meeting on Human Immunoglobulin Allotypic Markers. (1976) J. Immunogenet. 3. 

The X light chains have been shown to express a number of antigenic determinants which also reflect isotypic differences (Fett and Deutsch, 1975). Two distinct antigenic types of human X chains, termed Oz" and Oz , were originally thought to be allotypic markers (see below) but were later shown by genetic analyses to be isotypic in nature. Both types of chain are thus found in all normal individuals. The structural correlate... 

By far the greatest number of different allotypic markers have been found in man. Allotypes have also been found in a number of other species, however, including the rabbit, mouse, rat, cow, and chicken. For this chapter, we will be concerned mainly with structural correlates of human and rabbit allotypes. The general subject of allotypes is extremely well described in several excellent reviews (Mage et aL, 1973 Natvig and Kunkel, 1973 Kindt, 1975 Kunkel and Kindt, 1975), and the reader is directed to these for additional information. 

As yet, allotypic markers on human X light chains and the heavy... 

Table III. Localization of Certain Human Allotypic Markers"...

Localization of certain human allotypic markers. Refer to Fig. 1 for lineeir location within the heavy-chain constant region of the various IgG subclasses. 

Thus considerable progress has been made in identifying, characterizing, and locating the antigenic determinants associated with a number of human allotypic markers. These determinants are often quite complex with contributions from amino acids that are widely removed from one another in the linear sequence. This is therefore still another area where the details of the tertiary, or quaternary, structure of the immunoglobulin are crucial to the expression of a given function. 

This conclusion is also consistent with studies of Gm allotypic markers characteristic of human IgGl, which are detectable, among other primates, only in the serum of the great apes (129). In addition, allotypic markers characteristic of human IgG3 are found in the great apes and Old-World monkeys but not in the New-World monkeys (130). 

More recently, quantitative studies of percentages of immunoglobulin molecules bearing particular allotypic markers have been... 

Another type of radioimmunoassay (28-30) utilizes antiallotype antiserum rendered insoluble by polymerization with ethyl chloroformate. Such preparations bind I-labeled IgG or its fragments bearing the appropriate allotypic markers. The concentration of molecules bearing the allotype in an unlabeled preparation can be estimated through its capacity to inhibit binding of the labeled ligand. 

We will not attempt to describe research on allotypes in its historical context but, rather, will summarize present information. Table 9.1 lists the allotypic markers of rabbit immunoglobulins and their associa-... 

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