title: In vitro co-culture systems for studying molecular basis of cellular interaction between Aire-expressing medullary thymic epithelial cells and fresh thymocytes.
abstract: We previously established three mouse cell lines (Aire(+)TEC1, Aire(+)TEC2 and Aire(+)DC) from the medullary thymic epithelial cells (mTECs) and dendritic cells (mDCs). These cells constitutively expressed "autoimmune regulator (Aire) gene" and they exhibited various features of self antigen-presenting cells (self-APCs) present in the thymic medullary region. Here, we confirmed our previous observation that Aire(+) thymic epithelial cells adhere to fresh thymocytes and kill them by inducing apoptosis, thus potentially reproducing in vitro some aspects of the negative selection of T cells in vivo. In this system, a single Aire(+) cell appeared able to kill ∼30 thymocytes within 24 hrs. Moreover, we observed that ectopic expression of peripheral tissue-specific antigens (TSAs), and expression of several surface markers involved in mTEC development, increased as Aire(+) cell density increases toward confluency. Thus, these Aire(+) cells appear to behave like differentiating mTECs as if they pass through the developmental stages from intermediate state toward mature state. Surprisingly, an in vitro co-culture system consisting of Aire(+) cells and fractionated sub-populations of fresh thymocytes implied the possible existence of two distinct subtypes of thymocytes (named as CD4(+) killer and CD4(-) rescuer) that may determine the fate (dead or alive) of the differentiating Aire(+)mTECs. Thus, our in vitro co-culture system appears to mimic a part of "in vivo thymic crosstalk".
authors.affiliation: Advanced Research Center for Genome Super Power, Keio University, 2 Okubo, Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Advanced Research Center for Genome Super Power, Keio University, 2 Okubo, Tsukuba, Ibaraki 300-2611, Japan Laboratory of Gene Medicine, Keio University School of Medicine, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Kudoh
authors.affiliation: Institute for Advanced Sciences, Toagosei Company Limited, Tsukuba, Ibaraki 300-2611, Japan.
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Yoshida
authors.affiliation: Advanced Research Center for Genome Super Power, Keio University, 2 Okubo, Tsukuba, Ibaraki 300-2611, Japan smzgsp@dmb.med.keio.ac.jp.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Shimizu
keywords: AIRE; Aire+ cell lines; autoimmunity; central self-tolerance; thymic crosstalk