Ligation of MHC class I molecules on peripheral blood T lymphocytes induces new phenotypes and functions.
Microgram concentrations of immobilized anti-MHC class I (MHC-I) Ab induced proliferation of resting CD3+ T cells from peripheral blood. In contrast, soluble Ab did not activate T cells. Exposure of T cells to immobilized anti-MHC-I Ab for only 24 h was followed by proliferation and development of T cell-mediated cytotoxicity. Immediately following MHC-I ligation, the T cells responded with increased protein tyrosine phosphorylation, with new bands appearing in the SDS-PAGE. Exposure of T cells to immobilized anti-MHC-I Ab for 24 h induced an increased surface expression of the TCR/CD3 and CD28 molecules. MHC-I-induced proliferation of purified T cells was dependent on cellular interactions with non-T cells. Under certain conditions, in which MHC-I was ligated by picogram concentrations of immobilized anti-MHC-I Ab, anti-TCR/CD3 Ab-induced proliferation of T cells was strongly inhibited. These data clearly demonstrate that ligation of the MHC-I complex on T cells may induce both positive and negative signals. Since the physiologic ligands for MHC-I molecules are TCR and the CD8 molecules, our data may suggest that MHC-I molecules are instrumental in cellular interactions between T cells.
Bregenholt
S
S
Laboratory of Experimental Immunology, Department of Medical Anatomy, The Panum Institute, University of Copenhagen, Copenhagen, Denmark.
Röpke
M
M
Skov
S
S
Claesson
M H
MH
D000911:Antibodies, Monoclonal; D018106:CD28 Antigens / Q000502:physiology; D017252:CD3 Complex; D002455:Cell Division; D003602:Cytotoxicity, Immunologic; D004306:Dose-Response Relationship, Immunologic; D015395:Histocompatibility Antigens Class I / Q000378:metabolism / Q000502:physiology*; D006801:Humans; D066298:In Vitro Techniques; D010641:Phenotype; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D016176:T-Lymphocyte Subsets / Q000166:cytology* / Q000276:immunology; D013997:Time Factors
D000911:Antibodies, Monoclonal; D018106:CD28 Antigens; D017252:CD3 Complex; D015395:Histocompatibility Antigens Class I; D011948:Receptors, Antigen, T-Cell; D011505:Protein-Tyrosine Kinases