Human Vascular Endothelial Cells Stimulate Memory But Not Naive CD8+ T Cells to Differentiate into CTL Retaining an Early Activation Phenotype

Abstract

Endothelial cell (EC)-selective alloreactive CTL may mediate alloimmune vascular injury. In the present study, EC-selective CTL were generated in cocultures of purified human CD8+ T cells with allogeneic EC and were compared with conventional CTL against corresponding B lymphoblastoid cells (BLC). EC caused activation and expansion of memory but not naive CD8+ T cells, which differentiated into EC-selective CTL that retained high surface expression of CD69, CD25, and CD62L and displayed low intracellular perforin content. In contrast, BLC-stimulated CTL could be generated from naive or memory CD8+ T cells and showed a more mature phenotype (low CD69, CD25, and CD62L with higher levels of perforin). The expansion of alloreactive T cells by EC stimulation was 5- to 20-fold less effective than in corresponding BLC-stimulated cultures, accounting for a reduction in the assayable cytotoxicity of individual microcultures. In these IL-2-supplemented cocultures, no effect on CTL generation or phenotype was observed by mAb blocking of costimulation provided by LFA-3, ICAM-1, or CD40, by addition of comitogenic anti-CD28 mAb, or by preactivation of EC with CD40 ligand. Cyclosporine inhibited CTL expansion and cytotoxicity similarly in both EC- and BLC-stimulated cultures but did not affect the phenotype of those CTL that did emerge. This study extends the characterization of endothelium as an immunoregulatory cell type distinct from conventional APC and may explain why graft rejection within the arterial intima, an anatomic compartment in which EC may be the primary type of APC, is separable from rejection in the graft parenchyma.

Integration of Blood Outgrowth Endothelial Cells in Dermal Fibroblast Sheets Promotes Full Thickness Wound Healing

“…The need for exogenously added BOEC is underscored by the observation that the contribution of endogenous EC precursors is insignificant during wound vascularization [45]. Although allogeneic BOEC are more easily available, they have the capacity to initiate an immune response by resting allogeneic T-lymphocytes [46], necessitating the use of autologous BOEC. Autologous fibroblasts may however also be advantageous over allogeneic sources, since the latter were documented to increase scar formation and wound contraction [47].…”

Induction of inducible NO synthase in bystander human T cells increases allogeneic responses in the vasculature

“…The allogeneic response of CD8 T cells to human EC is mediated mainly by memory T cells and is characterized by T cell proliferation and the sustained expression of CD69 and HLA-DR (14). Dual-color flow cytometry indicated that all iNOS-expressing cells were CD8-positive.…”

“…CFSE Labeling and Cell Sorting. T cells were labeled with 1 M CFSE (Molecular Probes, Carlsbad, CA) before coculture with EC as described in SI Materials and Methods and either FACS sorted or analyzed as described previously (14).…”

“…Human umbilical vein EC, fibroblasts, and T cells were isolated and cocultured by using a T cell:EC ratio of 10:1 as described previously (14).…”

Transcription-controlled gene therapy against tumor angiogenesis

“…A recent report showed that the immune response against the transgene can be avoided by use of a liver-specific promoter (17). Since ECs perform poorly as APCs (18,19), we examined gene expression under the control of the PPE-1-3x promoter to see if it would reduce the humoral response against the transgene and increase transgene stability.…”