title: Localization of thymosin alpha 1 production to thymus medullary epithelial cells by use of monoclonal antibodies.
abstract: The thymus is an endocrine organ which modulates T-cell immunity through the production of protein like peptides such as the thymosins. Thymosin alpha 1 was the first biologically active peptide isolated and sequenced from the partially purified thymic preparation, thymosin fraction 5, and has been extensively studied. Using synthetic Thymosin alpha 1, a heterologous rabbit antiserum has been raised and a radioimmunoassay has been developed. Although thymosin alpha 1 antibodies have been used in several histological studies, their use is limited by potential nonspecific cross-reactivities, unpredictable heterogenicity, variable affinities, and a limited unstandardized supply. In the studies, reported here, eight anti-thymosin alpha 1 monoclonal antibodies (MAbs) were produced by somatic cell fusion between spleen cells from immunized BALB/c mice and P3x64 Ag8.653 myeloma cells. The MAbs were screened for anti-thymosin alpha 1 specificity in a solid phase ELISA and a liquid phase RIA. Only those clones which secreted specific antibody as detected by both procedures were characterized for their heavy chain class and epitope specificity. The anti-thymosin alpha 1 monoclonal antibodies were then used for indirect immune fluorescence studies of perfused rat thymus. Thymosin alpha 1 containing cells were found primarily in the thymic medulla, confirming previous studies using the heterologous antisera. These studies demonstrated the specificity of the anti-thymosin alpha 1 monoclonal antibodies for immunochemical studies of intra- and extra-thymic localization of thymosin alpha 1. They also provide an important reagent for biological studies of the role of thymosin alpha 1, in vitro and in vivo.
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D004797:Enzyme-Linked Immunosorbent Assay; D000939:Epitopes / Q000032:analysis; D006825:Hybridomas / Q000276:immunology; D051379:Mice; D010446:Peptide Fragments / Q000032:analysis / Q000276:immunology; D000077596:Thymalfasin; D013947:Thymosin / Q000031:analogs & derivatives* / Q000032:analysis / Q000276:immunology; D013950:Thymus Gland / Q000166:cytology*
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D010446:Peptide Fragments; D013947:Thymosin; D000077596:Thymalfasin