Structural components responsible for peptide antigenicity

The conformation of a peptide defines its antigenic specificity. In most ca ses, a free peptide is in a random form, whereas the same peptide within a protein has a defined conformation. Immunological cross-reactions between t he two are rare. Nevertheless, there are cases where an anticonformational antibody may transconform (change the conformation of) the free peptide, al lowing the reaction to occur. Based on such considerations, synthetic vaccines against infectious disease s may be constructed. The same is true for autoimmune diseases, where, at l east in one case-that of the exacerbating-remitting type of multiple sclero sis-we have developed a polypeptidic drug-vaccine, copolymer 1 (denoted Cop axone), capable of suppressing the autoimmune phenomena in a specific way. This drug-vaccine has been approved for treatment by the US Food and Drug A dministration (FDA).