Isolation of precursor endothelial cells from peripheral blood for donor-specific crossmatching before organ...

The clinical importance of endothelial-cell (EC) antibodies (Abs) in allo-transplantation (Tx) has been reported. However, lack of a suitable method for isolation of donor-specific ECs has prevented routine detection of these Abs before Tx. We describe a quick and simple method for the direct isolation of ECs from whole blood, for routine crossmatching (XM) to detect anti-EC Abs.

ECs were isolated using magnetic beads coated with Abs against the angiopoietin receptor Tie-2 that is expressed on EC precursors. A retrospective analysis of 50 previously well-characterized XM sera taken immediately before transplantation from patients with end-stage kidney disease were tested.

Tie-2+ cells expressed human leukocyte antigen (HLA) class I, class II, and other EC markers. Sera known to contain only EC-specific or EC- and monocyte (EM)-reactive Abs reacted positively with Tie-2+ cells but not with Tie-2- cells from the same individual. In addition, the Tie-2+ cells reacted with sera containing only HLA class I or class II Abs. In all, 3 of 25 sera from patients with stable graft outcome and no rejections reacted with Tie-2+ cells.

For the first time, with use of a single-target cell population, the detection of clinically relevant donor-specific HLA class I, class II, EM, and EC-specific Abs can be performed routinely before Tx. This method is promising because it is quick, specific, and easy to perform on whole blood samples and can therefore be used to perform routine donor-specific EC crossmatching (ECXM) in the future. Routine use of ECXM will aid in identifying better donor-recipient combinations and thus have a greater impact on transplant survival as compared with lymphocyte crossmatch (LXM).