Human vascular endothelial cells favor clonal expansion of unusual alloreactive CTL.
We have shown previously that cultured HUVEC or mixtures of endothelial cells (EC) and B lymphoblastoid cells (BLC) induce the differentiation of purified CD8+ PBL into allospecific, class I MHC-restricted CTL that lyse EC, but not BLC autologous to EC. Furthermore, these EC-selective CTL lines secrete little IFN-gamma after target cell contact. In the present study, we have analyzed these polyclonal populations at a single cell level by cloning at limiting dilution and propagating the resulting CTL clones in the absence of EC. Phenotypically stable, alloreactive EC-selective CTL preferentially emerge from cocultures in which EC or EC + BLC are the initial stimulating cell types compared with cocultures stimulated by BLC alone (p = 0.005). Compared with BLC-stimulated CTL, EC-stimulated CTL clones often fail to secrete IFN-gamma after target cell contact (p = 0.0006) and constitutively express CD40 ligand (CD40L) at rest (p = 0.0006). The absence of IFN-gamma secretion does not result from a switch to IL-4 secretion. The expression of CD40L inversely correlates with the secretion of IFN-gamma after target cell contact (p = 0.0001), but correlations of CD40L expression and failure to secrete IFN-gamma with EC-selective killing did not reach statistical significance. We conclude that in a microenvironment in which allogeneic EC are in close contact with infiltrating CD8+ T cells, such as within a graft arterial intima, CTL subsets may emerge that display EC selectivity or express CD40L and secrete little IFN-gamma after Ag contact.
Biedermann
B C
BC
Program in Molecular Cardiobiology, Boyer Center for Molecular Medicine, Yale University School of Medicine, New Haven, CT 06510, USA.
Pober
J S
JS
D002454:Cell Differentiation / Q000276:immunology; D002478:Cells, Cultured; D002999:Clone Cells / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D016207:Cytokines / Q000378:metabolism; D003602:Cytotoxicity, Immunologic / Q000276:immunology; D004730:Endothelium, Vascular / Q000166:cytology / Q000276:immunology* / Q000502:physiology; D006801:Humans; D016130:Immunophenotyping; D007519:Isoantigens / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology*; D011446:Prospective Studies; D012189:Retrospective Studies; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism
D016207:Cytokines; D007519:Isoantigens