IL-2-REGULATED EXPRESSION OF THE MONOCYTE CHEMOTACTIC PROTEIN-1 RECEPTOR (CCR2) IN HUMAN NK CELLS - CHARACTERIZATION OF A PREDOMINANT 3.4-KILOBASE TRANSCRIPT CONTAINING CCR2B AND CCR2A SEQUENCES

NK cells migrate in response to C-C chemokines, including monocyte che motactic protein-1 (MCP-1) and MCP-3. Increased migration was observed in IL-2-activated NK cells. It was therefore of interest to define th e expression in resting and activated NK cells of the MCP-1 receptor ( CCR2) for which two cDNAs (A and B) have been described. Specific olig onucleotides and reverse-transcriptase PCR revealed the presence in ac tivated NK cells and mononuclear phagocytes of the fragments expected on the basis of the reported cDNAs. In addition, amplification with a common A/B- and an A-specific oligonucleotide yielded an unexpected, a bundant, 1649-bp fragment. Sequence analysis as well as Northern blott ing and RNase protection with different probes revealed that the CCR2 gene is expressed in activated NK cells and mononuclear phagocytes asa predominant long transcript (3.4 kb) consisting of CCR2B, followed by a novel sequence (X), corresponding to an intron in the genome, and b y a CCR2A-specific portion. The predominant long transcript is polyade nylated and present in the cytoplasm. The augmented migratory capacity of IL-2 activated vs resting NK cells was associated with increased C CR2 transcript levels.