Role of immunolglobulin-like transcript family receptors and their ligands in suppressor T-cell-induced dendritic cell tolerization

The immunolglobulin-like transcript (ILT) family of proteins are surface receptors expressed by antigen-presenting cells capable of modulating host cell functions through intracellular signaling. Here we discuss the recent studies regarding the role of dendritic cell (DC)- expressed ILT receptors in suppressor T (Ts) cells induced DC tolerization. DC-expressed ILT3 and ILT4 are stimulated by their cognate ligands such as major histocompatibility complex class I (MHC-I), HLA-G, and CD1d, and this stimulation is a prerequisite for DC tolerization. The molecular interaction between ILT and ligands seems to create a tri-molecule complex at the interface between Ts cell and DC, which consists of DC-expressed ILT receptor and MHC-I, as well as T-cell-expressed T cell receptor (TCR). Furthermore, ILT4 recognition of MHC-I and CD1d is shown to be antigen dependent, suggesting that T-cell antigen specificity possibly affects the outcome of DC tolerization. Therefore the ILT-MHC interface could be a potential novel target for improving vaccine efficiency and allograft survival, or for devising new treatments for autoimmune diseases. (C) 2009 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.