CHROMOSOME MAPPING AND EXPRESSION OF THE HUMAN INTERLEUKIN-13 RECEPTOR

Interleukin-13 (IL-13) is a cytokine secreted by activated T cells and shares most but not all biological activities with interleukin-4 (IL- 4). Both cytokines play an important role as a switch factor directing synthesis of IgE; they act on monocytes and endothelial cells, but un like IL-4, IL-13 does not act on T cells. These cytokines have both co mmon and distinct components in their respective receptors. Based on s equence similarity shared by cytokine receptor family members, we have identified a cDNA encoding the human IL-13 receptor (IL-13R). This cD NA was used to examine the pattern of IL-13R mRNA expression by Northe rn blot analyses of poly(A)(+) RNA purified from different human tissu es and cell lines. Among several myeloma cell lines analyzed, the U266 cell line was the only one found to express IL-13R transcripts, This cell line is also the only one described as producing IgE, The IL-13R gene was mapped to chromosome Xq24 by in situ hybridization. Interesti ngly, this locus is near that of the CD40 ligand gene, the product of which is also involved, like IL-13, in proliferation and IgE isotype s witching of human B cells, The human IL-13R gene maps between two cyto kine receptor genes located on the chromosome arm Xq region: the inter leukin-a receptor gamma chain gene (Xq13.1) and the interleukin-9 rece ptor gene (Xq28), The lack of nucleotide sequence similarity suggests unrelated evolutionary pathways between these receptor genes. (C) 1997 Academic Press.