Biochemical and functional characterization of a molecule expressed by a subset of thymic medullary epithelial cells.
A monoclonal antibody (mAb), named TE-4F 10, was produced by fusing P3X-Ag8 myeloma cells with splenocytes of BALB/c mice immunized with a rat medullary thymic epithelial cell (TEC) line, (TE-R 2.5), previously established in our Institute. Flow cytometry showed that 85-95% TE-R 2.5 cells expressed the TE-4F10 antigen. The mAb immunoprecipitated a 29 kDa molecule from the TE-R2.5 cell lysate. Immunohistochemical analysis using single and double staining of the thymus with anti-cytokeratin (CK) mAb, showed that TE- 4F10 mAb selectively stains a subpopulation of medullary TEC. Hematopoietic and lymphoid cells were negative. The expression of the TE-4F10 antigen on TE-R 2.5 cells in vitro was significantly upregulated by interleukin 1 (IL-1) and tumor necrosis factor (TNFalpha). Other cytokines IL-4, IL-6, IL-10 and granulocyte - macrophage colony stimulating factor (GM-CSF) showed lesser stimulation on its expression, whereas interferon gamma (IFN) and dexamethasone were without significant effect. The TE-R 2.5 cell line strongly bound and induced apoptosis of a rat / mouse thymocyte heterohybridoma (BWRT8), phenotypically alphabetaTCRhiCD4hiCD8lo. TE-4F10 mAb significantly inhibited binding (40-50%) of both BWRT8 cells and the BWRT8 - MDP.1 subclone to TE-R 2.5 cells. The inhibition was enhanced when TEC were stimulated with IL-1 + TNFalpha. The mAb also significantly blocked apoptosis of BWRT8 but did not modulate cell death of the BWRT8 - MDP.1 subclone, which was resistant to TEC-induced apoptosis. These findings indicate that the TE-4F10 antigen might be selectively involved in adhesion and selection processes in the medullary thymic microenvironment. The mAb of the same characteristics has not been described so far.
Colić
M
M
Institute of Medical Research, MMA, Belgrade, Yugoslavia. vmaini@EUnet.yu
Vucević
D
D
Gasić
S
S
Popović
P
P
Milosavljević
P
P
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D000941:Antigens / Q000096:biosynthesis / Q000276:immunology* / Q000502:physiology; D017209:Apoptosis / Q000276:immunology; D016207:Cytokines / Q000276:immunology / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000276:immunology / Q000502:physiology; D005260:Female; D006801:Humans; D006825:Hybridomas / Q000276:immunology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D051381:Rats; D013194:Staining and Labeling / Q000379:methods; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology*
D000911:Antibodies, Monoclonal; D000941:Antigens; D016207:Cytokines