Phenotypic and functional characterization of lymphocytes that bind human microvascular endothelial cells in vitro. Evidence for preferential binding of natural killer cells.

Abstract

The microvascular endothelium has been postulated to be a critical target in the rejection of vascularized allografts. This study was undertaken to examine the ability of human sheep erythrocyte rosette forming lymphocytes (E-RFC) to form stable conjugates with microvascular endothelial cells (EC), and to assess whether a receptor-ligand interaction mediates this event. Human foreskin microvascular EC monolayers were used as targets of chromium-51-labeled E-RFC in a quantitative adherence assay. Binding was saturable, displaceable by unlabeled E-RFC, augmented by recombinant interleukin 1 (rIL-1) and inhibited by anti-LFA1 antibody. The Leu-11+ lymphocyte subset, known to be enriched for natural killer (NK) cells, bound preferentially. Only the EC-adherent lymphocyte fraction contained NK effectors, which lysed EC and classical NK targets. Thus, NK cells adhere to microvascular EC via a specific receptor-ligand interaction. The possibility exists that such binding occurs in recipients of vascularized allografts, representing the initial stage of graft rejection.