Human thymic epithelial cells present superantigens to T-cell lines and thymocytes.
It is generally accepted that thymic epithelial cells (TEC) act as accessory cells in positive selection of pre-T cells. However, our knowledge of the antigen presentation and accessory cell function to human TEC is limited. Here we present results obtained by the use of serum-free cultured human TEC, showing that IFN-gamma-treated TEC are able to support T-cell-mediated responses to the bacterial superantigens (Sag) SEA and SEB, even at very low Sag concentrations. T-cell responses to TEC-presented Sags were dependent on the presence of the adhesion molecules ICAM-1, ICAM-2, LFA-1, and LFA-3, but not on CD4 and CD8 molecules. There is a low but significant expression of B7 molecules on human TEC, and treatment of TEC with anti-B7.1 and anti-B7.2 antibodies before Sag pulsing leads to decreased Sag responses, indicating a significant importance of B7 molecules on TEC. Both CD4+ T-cell lines and CD4+ as well as CD8+ subpopulations of thymocytes showed significant responses, whereas nonseparated thymocytes, CD4+8+, and CD4-CD8- thymocytes did not respond or showed very low responses. In conclusion, the present results demonstrate that cultured human TEC are able to present Sag to thymocytes.
Jłrgensen
A
A
Institute of Medical Anatomy, University of Copenhagen, Panum Institute, Denmark.
Nielsen
M
M
Svejgaard
A
A
Ledbetter
J A
JA
Odum
N
N
Röpke
C
C
D000906:Antibodies / Q000276:immunology / Q000378:metabolism; D017951:Antigen Presentation / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology / Q000378:metabolism; D018122:B7-1 Antigen / Q000096:biosynthesis; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D015815:Cell Adhesion Molecules / Q000276:immunology / Q000378:metabolism; D002452:Cell Count; D002460:Cell Line; D002675:Child, Preschool; D004847:Epithelial Cells; D004848:Epithelium / Q000737:chemistry; D006801:Humans; D007223:Infant; D018089:Superantigens / Q000502:physiology; D016176:T-Lymphocyte Subsets / Q000276:immunology; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology; D013950:Thymus Gland / Q000737:chemistry / Q000166:cytology* / Q000276:immunology
D000906:Antibodies; D000942:Antigens, Bacterial; D018122:B7-1 Antigen; D015815:Cell Adhesion Molecules; D018089:Superantigens