Profile of human macrophage transcripts: insights into macrophage biology and identification of novel chemokines

High throughput partial sequencing of randomly selected cDNA clones has proven to be a powerful tool for examining the relative abundance of mRNAs and for the identification of novel gene products. Because of the important role played by macrophages in immune and inflammatory responses, we sequenced over 3000 randomly selected cDNA clones from a human macrophage library. These sequences represent a molecular inventory of mRNAs from macrophages and provide a catalog of highly expressed transcripts. Two of the most abundant clones encode recently identified CC chemokines. Macrophage-derived chemokine (MDC) plays a complex role in immunoregulation and is a potent chemoattractant for dendritic cells, T cells, and natural killer cells. The chemokine receptor CCR4 binds MDC with high affinity and also responds by calcium flux and chemotaxis. CCR4 has been shown to be expressed by Th2 type T cells. Recent studies also implicate MDC as a major component of the host defense against human immunodeficiency virus.