Heavy-Chain Variable Region Determinants

The exact position of the responsible subgroup-associated antigenic determinants within the heavy-chain variable domain is not yet clear. It seems obvious that they are not likely to be associated with the hypervariable regions (see below). Very probably they do involve, at least 

Feizi et al. (1977) have described a heavy-chain variable region marker (VnMar) that was detected using an antiserum raised against human IgM cold agglutinins. Evidence was presented that the relevant determinant was associable with cross-reactive idiotypes characteristic of the cold agglutinins. It was of particular interest that this antigen is found in both normal pooled IgG and some unselected myeloma paraproteins. 

The full expression of an idiotypic determinant is generally dependent on the presence of both the heavy and light chains of an immunoglobulin (e.g., see Carson and Weigert, 1973 Laskin et al., 1977). There are occasional examples, however, where a single chain can be shown to bear a given determinant. 

In addition to their intrinsic interest, idiotypic determinants have proven, and are continuing to prove, of great value in analyzing genetic aspects of the control of antibody synthesis, a topic that is beyond the scope of this chapter. 

One of the main contributions of the comparative, interspecies approach to the study of antibodies has been the demonstration that the 

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Antigenic Features of Immunoglobulins B. Heavy-Chain Variable Region Determinants... 

Fig. 12.7 Space-filling model of an IgG molecule. VL and VH variable domain light and heavy chain CL and CH constant domain light and heavy chain LCDR and HCDR complementarity-determining regions on VL and VH domains.

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