Different roles of D-amino acids in immune phenomena.
Peptides and polypeptides either fully or partially built of D-amino acids interest researchers because of their advantages over all L peptides and polypeptides. In exploiting these characteristics, one should realize that the resulting molecules are nonetheless not inert, but rather may induce a unique immune response, which is hardly cross-reactive with the L-enantiomer. Moreover, cross-reaction between the L- and the D-sequences is limited also at the T cell level, probably due to different sterical conformations of the MHC-antigen-T cell receptor complexes formed. Polypeptides built exclusively of D-amino acids lead to antibody formation only at a relatively low concentration, otherwise they provoke immunological paralysis. The specificity of the immune response toward peptides containing D-amino acid residues is exquisite, and often D-amino acids play a dominant role in defining the specificity. Polypeptides composed exclusively of D-amino acids are thymus-independent antigens. Nevertheless, it is possible to prepare against them highly specific T cell hybridomas. In future plans for synthetic vaccines against infectious or autoimmune diseases, the inclusion of D-amino acids may be an advantage in terms of both specificity and efficacy, the latter because of longer persistence in an undigested form because they resist enzymatic degradation.
Sela
M
M
Department of Immunology, The Weizmann Institute of Science, Rehovot, Israel.
Zisman
E
E
D000596:Amino Acids / Q000737:chemistry / Q000276:immunology* / Q000502:physiology*; D000818:Animals; D000939:Epitopes / Q000737:chemistry / Q000276:immunology / Q000502:physiology*; D006801:Humans; D010455:Peptides / Q000737:chemistry / Q000276:immunology* / Q000502:physiology*; D013237:Stereoisomerism
D000596:Amino Acids; D000939:Epitopes; D010455:Peptides