TY - JOUR T1 - FcϵRI-mediated thymic stromal lymphopoietin production by interleukin-4-primed human mast cells JF - European Respiratory Journal JO - Eur Respir J SP - 425 LP - 435 DO - 10.1183/09031936.00121008 VL - 34 IS - 2 AU - Y. Okayama AU - S. Okumura AU - H. Sagara AU - K. Yuki AU - T. Sasaki AU - N. Watanabe AU - M. Fueki AU - K. Sugiyama AU - K. Takeda AU - T. Fukuda AU - H. Saito AU - C. Ra Y1 - 2009/08/01 UR - http://erj.ersjournals.com/content/34/2/425.abstract N2 - A significant increase of mRNA expression of thymic stromal lymphopoietin (TSLP) has been reported in the bronchial mast cells (MCs) of asthmatic subjects; however, the mechanism underlying the upregulation of TSLP mRNA and protein remains unknown. FcϵRI-mediated activation of human MCs upregulated TSLP mRNA expression by 5.2±2.9-fold, while activation of the MCs using lipopolysaccharide and polyriboinosinic:polyribocytidylic acid failed to upregulate TSLP. Stimulation of MCs with interleukin (IL)-4 alone did not affect the TSLP mRNA expression, while pre-incubation of MCs with IL-4 for 48 h significantly enhanced the FcϵRI-mediated TSLP mRNA expression (by 53.7±15.9-fold; p<0.05) and the amount of TSLP in the cell pellets increased significantly from 23.4±4.3 pg·mL−1 to 121.5±3.7 pg·mL−1 (p<0.0001). However, the released TSLP was rapidly degraded by proteases that were released by MCs. We identified the population of cells expressing TSLP in the lungs of 16 asthmatic and 11 control subjects by immunohistochemistry. The percentage of TSLP-positive MCs in the total population of MCs was significantly increased in asthmatic airways (p<0.0001). Thus, MCs are able to store TSLP intracellularly and to produce TSLP following aggregation of FcϵRI in the presence of IL-4. ER -