The presence of activated CD4+ T‐Cells is essential for the formation of Colony Forming Unit‐Endothelial Cells (CFU‐EC) by CD14+ Cells

Abstract

The number of colony forming unit‐endothelial cells (CFU‐EC) in human peripheral blood was found to be a biological marker for several vascular diseases. In this study the heterogeneous composition of immune cells in the CFU‐EC was investigated. CFU‐EC cultures of mixtures of several populations were used to determine the cellular composition of the endothelial like colony. We confirmed that monocytes are essential for the formation of CFU‐EC. In addition, CD4+ T‐cells were found to be required for the induction of CFU‐EC. Blocking experiments showed that the interaction of MHC class II on the monocyte with the CD3/TCR complex on the T‐cell was involved in the support of colony formation by T‐cells. We showed that the contact‐induced T‐cell stimulation could be replaced by the supernatant, and thus the cytokines, of activated CD4 + T‐cells.Gene expression and protein analyses showed that colony formation represents a pro‐angiogenic differentiation of the monocytes, rather than an endothelial differentiation.In conclusion, CFU‐EC are derived from monocytes and are supported by CD4+ T‐cells. This in vitro study is the first to reveal the role of TCR/MHCII interactions between T‐cells and monocytes and the subsequent inflammatory response as stimulus of monocytic properties that are associated with vascularization.