Localization of human interleukin 13 receptor in non-haematopoietic cells.

Although the functional roles of interleukin (IL-)13 in haematopoietic cells are well investigated, those in non-haematopoietic cells remain to be addressed. IL-13 exerts its actions by binding to the IL-13 receptor (IL-13R) on target cells, which is composed of IL-13Ralpha1 and the IL-4 receptor alpha chain (IL-4Ralpha). However, there has been no study of localization of IL-13R in each tissue. To address this question, we generated monoclonal anti-IL-13Ralpha1 antibody, and performed immunohistochemistry using this antibody and anti-IL-4Ralpha antibody. Distribution of these two components was the same in all examined tissues. Staining was positive in keratinocytes, hair follicles, and sebaceous and sweat glands in skin; in ciliated respiratory epithelial cells in nasal tissue; in heart muscle cells; in foveola cells, gastric glands, and the smooth muscle layer in stomach; and in hepatocytes in liver. However, staining was undetectable in brain and bone marrow. Fibroblasts and endothelial cells were stained in some tissues. These results provide clues to elucidate the known pathological roles of IL-13 in atopic dermatitis and allergic rhinitis, as well as its unknown physiological roles.