A study from the Department of Biochemistry and Molecular Biology, University of Southern Denmark, and the Agricultural Research Council, Research Unit for Table Grapes and Wine Growing in Turi, Italy has identified a class of molecules called glycoproteins as the culprit. These are ubiquitous biological compounds that are comprised of a sugar portion (glyco-) attached to a protein. Examples include several hormones, connective tissue structures, and even antibodies. These molecules are commonly ensconced in the cell membrane, where they may help to identify what type of cell they are part of. Immune surveillance can be very tuned in to these molecules and so they are fairly common allergens. The Danish-Italian study identified some 28 different glycoproteins in wine with similarities to known plant allergens.
Unfortunately, glycoproteins in wine are derived from the grapes themselves as well as the yeast required for fermentation. It is possible that different strains of yeast might explain the differences in reactions to different wines (for example, people who are able to drink European wines but not the same varietal from a domestic producer), but using different yeasts would change the character of the wine. But this isn’t to say that nothing can be done. Hopefully some clever winemaker will target the market segment of those who would like to drink wine but can’t, and figure out some fining method or other means to remove glycoproteins from wine without sacrificing character. Clearly there is a lot more to learn about glycoproteins and wine allergy, but at least we now have something to go on.
Palmisano G, Antonacci D, Larsen MR. Glycoproteinomic profile in wine: A sweet molecular renaissance. J Protenome Res 2010 Oct 1; [epub ahead of print]