[Frontiers in Bioscience 16, 411-421, January 1, 2011]

Receptor-mediated T cell absorption of antigen presenting cell-derived molecules

Inkyu Hwang, DaLim Ki

The Scripps Research Institute, Department of Chemistry and Chemical Biology, 10550 North Torrey Pines Road, La Jolla, California 92037

TABLE OF CONTENTS

1. Abstract
2. Introduction
3. Historical background
4. Renewed interest in T cell absorption of APC-derived molecules
5. T cell absorption of APC-derived molecules via direct T/APC contact
5.1. Current views on the mechanism
5.2. In vivo T cell absorption of APC-derived molecules
5.3. Biological significance of ligand absorption
5.4. Application of ligand absorption
6. T cell absorption of pre-formed membrane vesicles released from APCs
6.1. Overview
6.2. Underlying mechanism(s) for pre-formed vesicle absorption
6.3. Application of pre-formed vesicle absorption
7. Acknowledgement
8. References

1. ABSTRACT

T cells tend to acquire a variety of cell surface molecules derived from antigen presenting cells (APCs). The molecule uptake occurs mainly during direct T/APC contact and is instigated by specific receptor/ligand interactions, such as T cell receptor (TCR) with a cognate peptide/MHC complex (pMHC) or CD28 with B7. The acquired molecules are targeted for internalization and degradation in the lysosome. Nevertheless, those molecules are expressed on the surface of T cells for a period of time. The presentation of APC-derived ligands by T cells exhibited a multitude of immunological effects via antigen-specific T/T interaction upon recognition of the absorbed antigens by contact with other T cells. Ligand uptake also occurs via absorption of membrane vesicles shed from APCs prior to contact (e.g., exosomes and plasma membrane-derived vesicles). As in ligand absorption via direct T/APC interaction, the absorption of pre-formed membrane vesicles is also dependent on specific receptor/ligand interactions. In this review, biological mechanisms underlying the ligand absorption process as well as the biological significance and application of the event will be discussed.