Antibodies to thymopoietin following implantation of paper disks derivatized with synthetic Cys-thymopoietin28–39

A synthetic peptide corresponding to Cys-thymopoietin 28-39 was synthesized and coupled by diazo linkages to aminophenyl thioether-derivatized paper disks. Disks were implanted in the peritoneal cavities of mice, initially after soaking in complete Freund's adjuvant and subsequently, at 3 week intervals, without further treatment. After four implantations, 6/6 mice developed antibodies reacting with the synthetic peptide and with native thymopoietin. In contrast, mice conventionally immunized with peptide alone (six mice) or with peptide complexed with thyroglobulin (six mice) all failed to develop antibodies. Mice immunized with disks derivatized with Cys-thymopoietin 9-20, corresponding to the other hydrophilic region of thymopoietin, also failed to develop antibodies. Thymopoietin 28-39 corresponds to an antigenic hydrophilic region of thymopoietin that contains the pentapeptide active site (thymopoietin 32-36, Arg-Lys-Asp-Val-Tyr).