Expression of a T cell receptor-like molecule on normal and malignant murine T cells detected by rat monoclonal antibodies to nonclonotypic determinants.
A T cell receptor-like molecule with a dimer structure of 45 kilodaltons (Kd) under reducing and 90 Kd under nonreducing conditions was detected on the surface of two murine T lymphoma lines, EL-4 and MBL-2, by two rat monoclonal antibodies. The two antibodies seemed to react with different determinants on the same molecule. The antibodies did not react with the surface of normal T cells as tested by flow cytometric analysis of cell surface staining. Two-dimensional gel electrophoresis (IEF vs SDS-PAGE) and tryptic peptide analysis revealed the molecule to consist of two chains with different isoelectric points and different tryptic peptides. A conventional antiserum was raised against the heterodimer purified from EL-4 cells. The immune serum did not bind to the surface of normal T cells. However, the immune serum as well as the monoclonal antibodies immunoprecipitated the dimer molecules from detergent-solubilized normal thymocytes and spleen cells. The dimer molecule was detected on both immature and mature thymocytes. These results suggest that the antibodies detect non-clonotypic determinants on a T cell receptor-like protein. The determinants are masked on the surface of normal T cells, whereas they are exposed on the surface of at least two T lymphoma cell lines. Three polypeptides of 30 Kd, 25 Kd, and 15 Kd were also coprecipitated with the heterodimer from MBL-2 cells. These proteins may associate with the heterodimer and may be masking the antigenic determinants on normal T cells. The relationship between the heterodimer molecule described here and the T cell antigen receptor or the human T cell antigen 9.3 is still unknown.
Chan
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Takei
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D000818:Animals; D000911:Antibodies, Monoclonal; D000937:Antigen-Antibody Reactions; D000951:Antigens, Neoplasm / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D000954:Antigens, Surface / Q000032:analysis / Q000276:immunology / Q000302:isolation & purification; D001666:Binding Sites, Antibody; D002460:Cell Line; D002999:Clone Cells / Q000378:metabolism; D000939:Epitopes / Q000276:immunology* / Q000302:isolation & purification; D007106:Immune Sera; D008223:Lymphoma / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011233:Precipitin Tests; D051381:Rats; D011916:Rats, Inbred F344; D011948:Receptors, Antigen, T-Cell / Q000032:analysis* / Q000276:immunology / Q000302:isolation & purification; D013601:T-Lymphocytes / Q000276:immunology / Q000378:metabolism*
D000911:Antibodies, Monoclonal; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D000939:Epitopes; D007106:Immune Sera; D011948:Receptors, Antigen, T-Cell