Effects of interleukin (IL)‐13 on immediate‐early response gene expression, phenotype and differentiation of human mast cells. Comparison with IL‐4

Abstract

The recently cloned interleukin 13 (IL‐13) shares most investigated biological activities on B lymphocytes and monocytes with IL‐4. In this study we investigated the potential role of IL‐13 in regulating human mast cell activities. The effects of IL‐13 on the expression of an immediate‐early response gene (c‐fos), proliferation, expression of mast cell‐associated cell surface antigen (CD54 and Kit), and in vitro differentiation of human mast cells, were investigated. We compared the effect of IL‐13 with that of IL‐4. Both IL‐13 and IL‐4 induced expression of c‐fos in cells from the human mast cell line HMC‐1. This indicates that mast cells express functional receptors for IL‐13. IL‐13 and IL‐4 decreased the proliferation rate of HMC‐1 cells. However, IL‐13 was less potent than IL‐4. Human mast cells constitutively express the adhesion molecule ICAM‐1 (CD54) and the receptor for stem cell factor (Kit) (CD117). The expression of CD54 was increased after treatment with IL‐13 or IL‐4, whereas the expression of Kit was decreased. Also in this action IL‐4 was more potent than IL‐13. By culturing mononuclear cells from cord blood in the presence of stem cell factor there is a differentiation of tryptase‐positive mast cells in the cultures. This process was inhibited when IL‐4 was present. In contrast, IL‐13 did not affect the expression of tryptase during differentiation of stem cell factor dependent cord blood‐derived mast cells. Taken together, these findings indicate that IL‐13 has regulatory effects on human mast cells. The effect overlaps with but is also different from that of IL‐4.