Shared antigens

The discovery of Lp(a) by Berg in 1962 (B6) relied on the production of rabbit antisera against beta-lipoprotein and on the selective absorption of these antisera with individual human sera. When certain human sera were used for absorption, the antisera retained precipitation capacity in radial immunodiffusion with 30-35% of individual human sera, which obviously contained a previous unknown antigen. The particle carrying the new antigen shared antigenic properties with beta-lipoprotein, but had an additional antigenic structure. This was evidenced from the only partial fusion of the precipitin bands formed between a positive human serum, the antibeta lipoprotein antiserum and the new absorbed antiserum. 

Parmiani N, et al. T-cell response to unique and shared antigens and vaccination of cancer patients. Cancer Immunol 2002 2 6. 

Dermietzel R, Leibstein A, Frixen U, Janssen-Timmen U, Traub O, Willecke K Gap junctions in several tissues share antigenic determinants with liver gap junctions. EMBO J 1984 3 2261-2270. 

Pollard, T. D. (1984). Purification of a high molecular weight actin filament gelation protein from Acanthamoeba that shares antigenic determinants with vertebrate spectrins. /. Cell Biol. 99, 1970-1980. 

Wood JG, Mirra SS, Pollock NJ, Binder LI (1986) Neurofibrillary tangles of Alzheimer disease share antigenic determinants with the axonal microtubule-associated protein tau (tau). Proc... 

Little is known about archaeal aminoacyl-tRNA synthetases, except that the phenylalanyl tRNA synthetases from the archaea Methanosarcina barkeri and S. acidocaldarius resemble their bacterial and eucaryal counterparts in being tetrameric proteins with an aggregate mass of 270 kDda. The archaeal enzymes, however, do not share antigenic determinants with the bacterial and eucaryal enzymes and are functionally restricted to tRNAs of their own lineage [13,14], Thus, they appear to constitute a third class of tRNA charging enzymes, evolutionarily distinct from those of the other domains. 

Familial Amyloidosis. Several genetically transmitted forms of amyloid disease have been reported. These have primarily neurological but also renal and vascular symptoms (Table 20-14), The fibrils of the Portuguese and Swedish syndromes and the polyneuropathic amyloid syndrome of Ashkenazic Jews have monomers of 14 kDa that share antigenic determinants and amino acid homology with prealbumin (transthyretin). 

The term immunoreactive insulin is used in reference to assays that may recognize, in addition to insulin, substrates that share antigenic epitopes with insulin. Examples include proinsulin, proinsuHn conversion intermediates, and insulin derivatives, produced by gly-cation or dimerization. 

These important results suggest that similarities or identities among monoclonal proteins may be found more frequently if they are selected for comparison on the basis of shared antigen-binding specificity. This possibility is supported by studies with mouse myeloma proteins, reviewed later in this chapter. 

Amyloid proteins related to immunoglobulin possess individually specific (idiotypic) antigenic determinants i.e., such amyloid proteins from different individuals possess unique primary structures. Idiotypic determinants characteristic of a given amyloid protein can sometimes be detected in the serum of the same individual. In addition, however, amyloid proteins of a given type (it or X) frequently have shared antigenic determinants (120,124,126). Antiserum directed to an amyloid protein will, in general, cross-react weakly with normal L chains of the same type. It seems likely that these cross-reactions are attributable, in the case of the smaller amyloid proteins, to shared V region sequences. 

Shared antigenic determinants in the IgE of mammalian species are discussed in the next section. 

The IgG molecules of all rabbits share antigenic determinants which are absent, for example, from bovine IgG. These are the isotypic determinants. (The IgG molecules of the two species share other antigenic specificities.)... 

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