Adhesion molecules of cultured hematopoietic malignancies . A calcium-dependent lectin is the principle mediator of binding to the high endothelial venule of lymph nodes

This study documents that a calcium-dependent phosphoman-nosyl-binding site on human lymphoid malignancies mediates attachment to the peripheral node high endothelial venule (PNHEV). The phorbol ester PMA coordinately upregulates lectin activity and binding to the PNHEV in the human T-lym-phoblastic cell line Jurkat but not in the less phenotypically mature lines HSB2, Molt4, CEM, and HPB-ALL. In contrast, expression of CD18, CD2, and several common epitopes of the putative adhesion receptor gp90fIerme (CD44) did not correlate with attachment to PNHEV in this series of cell lines. Insensi-tivity to inhibition by the CD18 MAb TS 1.18, temperature and divalent cation requirements further distinguish the Jurkat-PNHEV adhesive interaction from CD11a/18- and CD2-me-diated adhesion. The PMA-induced phenotypic changes in the Jurkat line parallel late thymocyte differentiation as well as lymphocyte activation, suggesting that expression of the endo-thelial-binding lectin may be linked to one or both of these processes. The lectin-like activity on Jurkat cells is function-ally indistinguishable from those previously linked to PNHEV recognition in normal human lymphocytes, normal rat lym-phocytes and both normal and malignant murine lymphoid cells. In the mouse, this activity is either contained in or func-tionally linked to a member of the LEC-CAM family gp9OMeIl4, suggesting that Jurkat cells express the human ho-mologue of the murine nodal homing receptor. Thus cultured T lymphoblastic malignancies express a variety of potential en-dothelial adhesion molecules but use primarily a highly con-served surface lectin to interact with PNHEV