MONOCYTE CHEMOATTRACTANT PROTEIN-1 GENE IS EXPRESSED IN ACTIVATED NEUTROPHILS AND RETINOIC ACID-INDUCED HUMAN MYELOID CELL-LINES

We have used differential display polymerase chain reaction to identif y genes that are upregulated after retinoic acid (RA) treatment of hum an myeloblastic HL-60 cells. Three of the cDNAs cloned hybridized to R A-inducible transcripts on Northern blots, one of which was shown to e ncode sequences for monocyte chemoattractant protein-1 (MCP-1), a rece ntly described cytokine that is chemotactic for monocytes but not for neutrophils. Nuclear run-on analysis indicated that the upregulation o f the MCP-1 gene occurs at the transcriptional level in HL-60 cells. M CP-1 transcript levels also increased after RA treatment of the NB4 ac ute promyelocytic cell line. MCP-1 transcripts were undetectable in fr eshly isolated neutrophils by Northern analysis or reverse transcripti on-polymerase chain reaction but were readily detectable in neutrophil s after incubation in media at 37 degrees C for 20 hours, suggesting t hat an activation event can lead to MCP-1 expression in neutrophils. I mmunocytochemistry confirmed the presence of MCP-1 protein in activate d neutrophils. This is the first report that the MCP-1 gene is RA-resp onsive in myeloid cell lines and is expressed in neutrophils. MCP-1 ex pression by activated neutrophils may play an important role in attrac ting monocytes to the site of tissue damage or infection. (C) 1994 by The American Society of Hematology.