Antigen presentation by parenchymal cells: a route to peripheral tolerance?
T-cell activation and the development of efficient immune responses requires the delivery, by the antigen-presenting cell, of two distinct signals. The first results from the engagement of the TCR:CD3:CD4 complex, and the second from the interaction of CD28 with the B7 family of co-stimulatory molecules. In this context, the physiological significance and the functional consequences of antigen presentation by B7-deficient parenchymal cells, which express MHC class II molecules as a result of inflammation, remains a matter of debate. In this paper we have attempted to critically review the often conflicting reports on the functional effects of antigen presentation by epithelial and endothelial cells to T cells, both in vitro and in vivo. Our own findings are summarised in a model which is consistent with the suggestion of an important role for antigen presentation by parenchymal cells in the induction and the maintenance of peripheral tolerance.
Marelli-Berg
F M
FM
Department of Immunology, Imperial College School of Medicine, London, UK.
Lechler
R I
RI
D000069594:Abatacept; D000818:Animals; D017951:Antigen Presentation; D000938:Antigen-Presenting Cells / Q000276:immunology; D015703:Antigens, CD; D000943:Antigens, Differentiation / Q000378:metabolism; D018106:CD28 Antigens / Q000378:metabolism; D060908:CTLA-4 Antigen; D004727:Endothelium / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology; D006801:Humans; D007108:Immune Tolerance; D018796:Immunoconjugates; D008213:Lymphocyte Activation; D008954:Models, Biological; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000276:immunology; D014181:Transplantation Immunology
D015703:Antigens, CD; D000943:Antigens, Differentiation; D018106:CD28 Antigens; D060908:CTLA-4 Antigen; C556706:CTLA4 protein, human; D018796:Immunoconjugates; D000069594:Abatacept