doi:10.1006/cyto.2001.0958, available online at http://www.idealibrary.com on GENE EXPRESSION PROFILES FOR FcRI, CYTOKINES AND CHEMOKINES UPON FcRI ACTIVATION IN HUMAN CULTURED MAST CELLS DERIVED FROM PERIPHERAL BLOOD Shunichi Wakahara, 1 Yasuyuki Fujii, 1 Toru Nakao, 2 Katsuki Tsuritani, 1 Toshifumi Hara, 1 Hirohisa Saito, 3 Chisei Ra 4 Mast cells have been reported to release not only chemical mediators, but also cytokines upon Fc receptor I(FcRI) cross-linking. Recently, we have established a culture system to derive chymase-rich human mast cells from mononuclear cells in peripheral blood. However, the functional properties of these mast cells have remained unrevealed. In this study, we examined the functions of peripheral blood-derived human cultured mast cells (pHCMCs). pHCMCs expressed functional FcRI, and most of them contained tryptase. These pHCMCs sensitized with immunoglobulin E (IgE) and interleukin 4 (IL-4) were activated through cross-linking of FcRI. The time-dependent mRNA expression profiles of FcRI subunits, cytokines and chemokines in the sensitized pHCMCs upon FcRI engagement were examined by reverse transcriptase polymerase chain reaction (RT-PCR). mRNA for most of cytokines and chemo- kines, which were observed in allergic inflammation, was detected in activated pHCMCs. In addition, gene expression for monocyte chemoattractant protein 3 (MCP-3) in human mast cells, and liver and activation-regulated chemokine (LARC), thymus and activation-regulated chemo- kine (TARC) and macrophage-derived chemokine (MDC) in mast cells was revealed for the first time in our study. FcRI-mediated cytokine and chemokine production at protein level was evaluated using enzyme-linked immunosorbent assay (ELISA). These data suggest that pHCMCs, which are capable of producing a variety of cytokines and chemokines, can be a useful candidate for investigating roles of mast cells as a conductor for allergic inflammation.  2001 Academic Press Effector phase of type-I allergy begins with degranulation of mast cells through Fc receptor I (FcRI) cross-linking, and is followed by a series of late-phase reactions. As part of late-phase reactions, inflammatory cells, such as lymphocytes, eosinophils and basophils, are recruited into the site of allergic inflammation. 1 The recruitment of inflammatory cells in late-phase allergic reactions is well controlled in a time dependent manner, 2 suggesting that there may be some conductor cells. Mast cells release not only chemical mediators (histamine, leukotrienes and prostaglandins), but also cytokines upon FcRI engagement. The expression of cytokines, interleukin 4(IL-4), IL-5, IL-6, IL-8, tumour necrosis factor  (TNF-) and IL-13, has been reported in human lung, 3 skin 4 and intestinal tissue mast cells, 5,6 and mast cells are suggested to be a candidate of conductor cells. However, little is known about actual roles and functions of human mast cells in the course of allergic reaction because of difficulties in purification of primary cells, and the lack of appropriate cell lines. A culture system to derive human mast cells was established from CD34 + cells in umbilical cord blood. 7 The cord blood-derived human cultured mast cells (cHCMCs) expressed functional FcRI, most of them contained tryptase, and showed degranulation capacity and cytokine production through FcRI engagement. From the 1 Molecular Biology Laboratory, Medicinal Research Laboratories, Taisho Pharmaceutical Co., Ltd, Saitama, Japan; 2 Ethical Business Strategy Division, Taisho Pharmaceutical Co., Ltd, Saitama, Japan; 3 Department of Allergy and Immunology, National Children’s Medical Research Center, Tokyo, Japan; 4 Department of Molecular Cell Immunology and Allergology, Advanced Medical Research Center, Nihon University School of Medicine, Tokyo, Japan Correspondence to: Toru Nakao, the Ethical Business Strategy Division, Taisho Pharmaceutical Co., Ltd, 403, Yoshino-cho 1-chome, Saitama-shi, Saitama, 330-8530, Japan. Tel: + 81 48 651 6245; Fax: +81 48 663 2145; E-mail: t.nakao@po.rd.taisho.co.jp Received 2 October 2000; received in revised form 21 May 2001; accepted for publication 11 August 2001  2001 Academic Press 1043–4666/01/220143+10 $35.00/0 KEY WORDS: chemokines/cytokines/FcRI/gene expression/ human mast cell CYTOKINE, Vol. 16, No. 4 (21 November), 2001: pp 143–152 143