title: Thymus-independence of slowly metabolized immunogens.
abstract: The role of thymus in antibody responses to a series of four synthetic polypeptide immunogens of the general formula multi-copoly(Tyr,Glu)-poly(Pro)-poly(Lys) was investigated as a function of the optical activity of the amino acids composing their structure. Irradiated nonthymectomized and thymectomized SJL mice were injected with thymocytes, marrow cells, or a mixture of both. Each group of recipients was immunized with the following copolymer enantiomorphs: all L-amino acids; L-amino acids outside and D inside; D-amino acids outside and L inside; or all D-amino acids. The antibody response to the immunogen composed of all L-amino acids was thymus-dependent, whereas the responses to the other three copolymers were all independent of the thymus. Similar cell transfers were performed in DBA/1 mice immunized with multi-copoly(L-Phe,L-Glu)-poly(D-Pro)-poly(D-Lys). This mouse strain produces specific antibodies against the (Phe,Glu) region and against the poly(D-prolyl) region. The immune response to the determinant with only L-amino acids on the outside was thymusdependent, whereas the response to the inside immunopotent region with only D-amino acids was thymusindependent. Since earlier studies have demonstrated that synthetic polypeptide antigens that contain D-amino acids are poorly metabolized, the thymus-independence of the antibody responses to these multichain synthetic polypeptides that possess repeating antigenic determinants was correlated with the metabolizability of the immunogens or their component determinants.
mesh_terms: D000818:Animals; D000917:Antibody Formation; D000941:Antigens; D001854:Bone Marrow Cells; D003036:Cobalt Isotopes; D000939:Epitopes; D004912:Erythrocytes; D005260:Female; D005971:Glutamates; D006386:Hemagglutination Tests; D008239:Lysine; D051379:Mice / Q000276:immunology; D008815:Mice, Inbred Strains; D008961:Models, Structural; D009904:Optical Rotation; D010455:Peptides; D011392:Proline; D011830:Radiation Effects; D012756:Sheep / Q000276:immunology; D013237:Stereoisomerism; D013934:Thymectomy; D013950:Thymus Gland / Q000166:cytology / Q000502:physiology*; D014443:Tyrosine
chemical_list: D000941:Antigens; D003036:Cobalt Isotopes; D000939:Epitopes; D005971:Glutamates; D010455:Peptides; D014443:Tyrosine; D011392:Proline; D008239:Lysine