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BioMed Research International
Volume 2014 (2014), Article ID 215763, 9 pages
Research Article

The Soluble Form of CTLA-4 from Serum of Patients with Autoimmune Diseases Regulates T-Cell Responses

1Section of Human Anatomy, Department of Experimental Medicine, University of Genoa, Via De Toni 14, 16132 Genoa, Italy
2Departments of Medicine and Cell Biology, North Shore University Hospital, Manhasset, NY 11030, USA
3Autoimmunity Unit, Department of Internal Medicine, University of Genoa, 16132 Genoa, Italy
4Laboratory of Clinical Pathology, San Antonio Hospital, Tolmezzo, 33100 Udine, Italy

Received 30 April 2013; Revised 30 October 2013; Accepted 31 October 2013; Published 29 January 2014

Academic Editor: Koji Kawakami

Copyright © 2014 Rita Simone et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Cytotoxic T lymphocyte associated antigen-4 (CTLA-4) is a costimulatory receptor transducing a potent inhibitory signal. Increasing evidence showed that CTLA-4 gene is an important susceptibility locus for autoimmune disorders. Alternatively spliced mRNA generates a soluble form, called sCTLA-4. Whereas low levels of sCTLA-4 are detected in normal human serum, increased/high serum levels are observed in several autoimmune diseases. The biological significance of increased sCTLA-4 serum level is not fully clarified yet. It can be envisaged that sCTLA-4 specifically inhibits the early T-cell activation by blocking the interaction of CD80/CD86 with the costimulatory receptor CD28. On the other hand, higher levels of sCTLA-4 could contend the binding of the membrane form of CTLA-4 with CD80/CD86, in later activation phase, causing a reduction of inhibitory signalling. We showed that sCTLA-4 from sera of patients with different autoimmune diseases is able to display functional activities on an in vitro system acting on the proliferation capability and modulating the secretion of cytokines. We observed a dual effect of sCTLA-4: inhibiting the secretion of IFN-γ, IL-2, IL-7, and IL-13 and activating the secretion of TGF-β and IL-10. This study underlines the role of sCTLA-4 in modulating the immune response and its relevance in autoimmune disease pathogenesis.