Regulation of effector T cells by antigen-presenting cells via interaction of the C-type lectin MGL with CD45

Nature Immunology. 7, 1200 - 1208 (2006)

Speaker: 李明翰                         Time:14:10~15:00, Dec. 13, 2006

Commentator: 黎煥耀 老師                Place: Room 601

Abstract：

Antigen-presenting cells (APCs) such as dendritic cells (DCs) and macrophages reside in peripheral tissues, where they screen their environment for pathogens or changes in immune homeostasis (1). APCs express exclusive sets of C-type lectin receptors (CLRs) that recognize specific carbohydrate moieties in a calcium-dependent manner (2). SomeCLRs are important in controlling immune homeostasis by clearing self antigen and inducing tolerance. A CLR, macrophage galactose-type lectin (MGL), is expressed exclusively by myeloid APCs such as immature DCs and alternatively activated macrophages. In this study, the authors tried to define potential counter-receptors for human MGL on immune cells. They constructed a chimeric molecule consisting of the extracellular domain of MGL fused with IgG1 Fc tail. Using this molecule for immunoprecipitation andimmunoblotting, they identified CD45 as a counter-receptor for MGL. They found that MGL interacted with CD45 on effector T cell to suppress cell proliferation. This interaction reduced CD45 phosphatase activity and inhibited Lck activation and calcium mobilization. MGL-mediated downregulation of effector T cell activation was associated with reduced inflammatory cytokine production and increased T cell death. Thus, the authors demonstrate an important function for CLRs on APCs in the regulation of T cell homeostasis and the silencing of potentially harmful T cell activation.

References:

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2. Figdor, C.G., van Kooyk, Y. and Adema, G.J. C-type lectin receptors on dendritic cells and Langerhans cells. Nat. Rev. Immunol. 2, 77-84 (2002)