title: Immunohistological analysis of thymic tumors with PE-35 monoclonal antibody reactive with medullary thymic epithelium.
abstract: PE-35 mouse monoclonal antibody (MoAb) (IgG1) detecting an epithelial antigen with a molecular weight of 35,000 was characterized serologically. Immunoperoxidase staining and double immunoenzymatic staining showed that PE-35 antigen is predominantly on nonlymphoid cells in the medulla of thymus. By immunoelectron microscopy, thymic epithelial cells in the medulla were positive with PE-35 MoAb, but macrophages, interdigitating reticulum cells, and thymocytes were negative with this MoAb, which demonstrated that PE-35 is a valuable marker for medullary epithelium. Using PE-35 and other MoAbs detecting thymic epithelial antigens (TE-3A, RFD-4, TE-4, and HLA-DR), 25 thymomas were studied, together with 6 other tumors of thymic origin. Among 25 thymomas, all 6 cases of epithelial type and 8 of 14 mixed lymphoepithelial type were positive with PE-35 MoAb, but only one of 5 lymphocytic type was positive. PE-35 antigen has a tendency to be expressed in the cases retaining medullary type thymocytes, with the phenotype of cluster of differentiation (CD) 1-/CD3+/CD6+, and also in the area of medullary differentiation. TE-3A, RFD-4, and TE-4 MoAbs reacted with most thymoma cases regardless of the types. HLA-DR was, however, expressed on a part of thymomas and the phenotype combined with that of PE-35 was as follows: PE-35+/HLA-DR+, 8 cases; PE-35+/HLA-DR-, 8 cases; PE-35-/HLA-DR+, 8 cases; PE-35-/HLA-DR-, one case. The results suggested that thymoma may originate from different subsets and/or different stages of thymic epithelium.
mesh_terms: D000911:Antibodies, Monoclonal / Q000276:immunology*; D000918:Antibody Specificity; D000951:Antigens, Neoplasm / Q000032:analysis*; D004848:Epithelium / Q000276:immunology; D000939:Epitopes; D006801:Humans; D007124:Immunoenzyme Techniques; D007130:Immunoglobulin Idiotypes / Q000276:immunology; D008854:Microscopy, Electron; D008970:Molecular Weight; D009363:Neoplasm Proteins / Q000276:immunology; D013945:Thymoma / Q000276:immunology*; D013950:Thymus Gland / Q000276:immunology; D013953:Thymus Neoplasms / Q000276:immunology*
chemical_list: D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000939:Epitopes; D007130:Immunoglobulin Idiotypes; D009363:Neoplasm Proteins