New roles of mast cells in allergic inflammation

Abstract

Mast cells have been recognized as one of the most important effector cells in IgE-dependent allergic reactions. Recently, the relationship between mast cells and fibroblasts has been indicated in the process of fibrotic conditions. Actually the number of mast cells is increased in the specimens obtained from fibrotic diseases, such as the involved skin of keloid and the forearm in an early stage of systemic sclerosis. Our studies showed that activation of human mast cells, which were generated from cord blood in the presence of stem cell factor and interleukin 6, increased [3H] thymidine incorporation into human fibroblasts, indicating that the mast cells possess a proliferating activity on fibroblasts. Tryptase has been indicated as one of the fibrogenic factors. In addition, our studies showed that cord blood-derived human cultured mast cells constitutively express mRNA for transforming growth factor β1, which can be involved in fibrotic conditions. These data indicate that mast cell is now being recognized to play new roles in allergic inflammation.