A novel 4-kb interleukin-13 receptor alpha mRNA expressed in human B, T, and endothelial cells encoding an alternate type-II interleukin-4/interleukin-13 receptor.

A 4 kb human interleukin-13 receptor (IL-13R) chain cDNA was cloned from a B cell cDNA library using expressed sequence tags homologous to mouse IL-13R as probes. The deduced protein sequence shows a significant level of sequence identity with the IL-5R and the human IL-13R identified recently by expression cloning. The cytoplasmic region is very highly conserved between human and mouse homologs and contains a consensus binding motif for a signal transducer and activator of transcription. The cDNA encodes a protein binding IL-13 when expressed alone which participates in a receptor complex for both IL-4 and IL-13 when expressed in conjunction with the IL-4R alpha chain. Transcripts for this IL-13R chain could be detected in most tissues and organs studied and in T, B, endothelial cells, basophilic, immature mast cell, and monocytic cell lines. The pattern of expression is different from the other recently cloned IL-13R molecule, and correlates with sites where IL-4 and IL-13 signaling is known to occur. This novel receptor is therefore likely to be implicated in reactions involved in IgE responses, T helper 2 differentiation, adhesion of leukocytes to endothelium, and therefore in pathological phenomena such as allergy, atopy, and asthma.