Monocyte chemotactic protein-1 in the migration of differentiated leukaemic cells toward alveolar epithelial cells.

All-trans retinoic acid (ATRA) can induce acute respiratory distress syndrome in patients with acute promyelocytic leukaemia (APL). The current study investigated the role of monocyte chemotactic protein (MCP)-1 in the chemotactic transmigration of ATRA-treated NB4 (ATRA-NB4) APL cells toward A549 alveolar epithelial cells. NB4 and A549 cells were separately cultured with ATRA and/or dexamethasone (DEX). ATRA-NB4 cells were then placed in an upper insert and co-incubated with A549 cells or their conditioned medium (CM) located in a lower plate to test their transmigration activity. ATRA stimulated NB4 cells to transmigrate toward the A549 cells. The secretion of MCP-1 was enhanced by ATRA treatment in both A549 and NB4 cells. The binding assay demonstrated that ATRA-NB4 cells bound MCP-1. Pre-treatment of both CM-A549 cells with antibodies against MCP-1 and of ATRA-NB4 cells with antibodies against MCP-1 receptors reduced ATRA-NB4 cell transmigration. DEX did not suppress MCP-1 secretion and transmigration in ATRA-NB4 cells, although when applied to A549 cells, MCP-1 secretion was suppressed and ATRA-NB4 cell transmigration was attenuated. Monocyte chemotactic protein-1 secreted from alveolar epithelial cells plays an important role in the cell-cell interaction involved in the chemotactic transmigration of all-trans retinoic acid-treated acute promyelocytic leukaemia cells toward alveolar epithelial cells.