Regulation of T:B cell interactions by the Inducible Costimulator molecule: Does ICOS “induce” disease?

• Published in: Clinical Immunology 2006-10, Vol.121 (1), p.13-18
• Main Authors: Shilling, Rebecca A., Bandukwala, Hozefa S., Sperling, Anne I.
• Format: Article
• Language: English
• Subjects: Allergy; Animals; Antigens, Differentiation, T-Lymphocyte - physiology; Asthma; Autoimmune Diseases - metabolism; Autoimmunity; B cells; B-Lymphocytes - immunology; B-Lymphocytes - metabolism; Biological and medical sciences; Cell Communication - immunology; Follicular T helper Cells; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Humans; Humoral immunity; Hypersensitivity - immunology; Hypersensitivity - metabolism; ICOS; Immunopathology; Inducible T-Cell Co-Stimulator Protein; Medical sciences; Polymorphisms; T cells; T-Lymphocytes - immunology; T-Lymphocytes - metabolism
• ISSN: 1521-6616; 1521-7035; 1365-2567
• DOI: 10.1016/j.clim.2006.04.574

The Inducible Costimulator molecule (ICOS), a member of the CD28 family of costimulatory molecules, was identified in 1999 as a molecule expressed primarily on activated human T cells. Induced upon activation, ICOS appears to be an ideal target for modifying T-cell-mediated immune responses. ICOS was also found to be highly expressed on germinal center T cells, suggesting that ICOS was involved in T:B cell interactions. While ICOS has subsequently been shown to be important for both Th1 and Th2 cell activation and effector function, a central role for ICOS in the generation and maintenance of humoral immunity is emerging. In this review, we summarize the evidence that the level of ICOS expression regulates T-cell-dependent B cell responses and propose a model for the role of ICOS in diseases characterized by dysregulated humoral immunity.