Accurate identification of paraprotein antigen targets by epitope reconstruction

Abstract

We describe the first successful clinical application of a new discovery technology, epitope-mediated antigen prediction (E-MAP), to the investigation of multiple myeloma. Until now, there has been no reliable, systematic method to identify the cognate antigens of paraproteins. E-MAP is a variation of previous efforts to reconstruct the epitopes of paraproteins, with the significant difference that it provides enough epitope sequence data so as to enable successful protein database searches. We first reconstruct the para-

A frequent target of paraproteins in the sera of patients with multiple myeloma and MGUS

“…Epitope specificity was also determined by ELISA using recombinant full-length paratarg-7 and recombinant fragments of paratarg-7 as a coat. All 29 paratarg-7 reactive paraproteins were tested by this ELISA and all reacted with recombinant paratarg-7 1-36 and paratarg-7 [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] confirming the epitope specificity obtained with the peptide spot assay (Fig. 4).…”

“…15 Even though few of these studies convincingly proved that the observed phenomena were indeed caused by binding of the respective paraprotein to its specific antigenic target (e.g., by ''reverse Western'' blotting and/or sequencing of the target antigen as done in this study), these selective observations are often cited to support a causal relationship between the development of an MGUS or MM clone and chronic antigenic stimulation. [1][2][3][4][5][16][17][18][19][20][21][22][23] Similarly, doubts are raised about the paraprotein-mediated reactions with antigens predicted by epitope reconstruction and reported in a recent paper, 24 because the reactions were observed at concentrations of the paraprotein-containing serum of only 1:2,500. In contrast to these reports, our first systematic studies 7,8 did not only convincingly prove the paraprotein-mediated reactivity against the identified antigens, it also revealed a broad spectrum of antigenic targets of paraproteins.…”

Waldenström Macroglobulinemia: Clinical and Immunological Aspects, Natural History, Cell of Origin, and Emerging Mouse Models

“…This will hopefully change in the near future as—in addition to expression cloning [145] used in the “paratarg” studies described in Section 3.4—new methods have been developed that lend themselves to identifying and validating specific antigens/haptens recognized by WM-associated mIgM. Epitope-mediated antigen prediction (E-MAP) [148] and high-density peptide microarrays [149] are two promising methods to that end. It is possible that both endogenous (self) antigens and exogenous (microbial) antigens trigger WM.…”

Pathophysiology of Waldenstrom's macroglobulinemia

“…Epitope-mediated antigen prediction technology may identify antigens reacting with paraprotein antibodies. 30 Identification of these antigens could provide insights into the process by which cells become malignant in WM.…”