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Mediators of Inflammation
Volume 2005, Issue 3, Pages 160-166

Inflammatory Process of CD8+CD28 T Cells in Induced Sputum From Asthmatic Patients

1Department of Pediatric and Respiratory Diseases, Abderahmane Mami Hospital, Pavillon B, Ariana, 2080, Tunisia
2Homeostasis and Cell Dysfunction Unit Research 99/UR/08-40, Medicine University of Tunis, Secretary of State of Scientific Research and Technology, Tunis 1007, Tunisia

Received 26 January 2005; Accepted 22 February 2005

Copyright © 2005 Hindawi Publishing Corporation. 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.


Previously unreported CD8+CD28 and CD8+CD28+ T-cell subsets occur in healthy individuals and expand in patients suffering from autoimmune disease. Here we studied, for the first time, the expression of CD8+CD28+, CD8+CD28-, and CD8+CD56+ subpopulations in induced sputum from asthmatics. Using sputum samples, purified CD8+ T cells were stained for surface antigen CD28, CD56, FITC-conjugated anti-perforin, and anti-IFN-γ. Cytotoxic activity was evaluated in a chromium releasing test. Induced sputum CD8+CD28- T cells were found to be more expanded and expressed low levels of IFN-γ in severe asthmatics than mild asthma and age-matched healthy controls. The predominance of CD8+CD28- T cells can be in part explained by the expansion of CD8+CD56+. CD8+CD28- T cells from severe asthmatics produced high intracytoplasmic perforin and exerted a potent cytotoxic activity. Considering their phenotyping and functional properties, the CD8+CD28- T-cell subset may constitute an intermediate phenotype in the process of CD8+ T-cell differentiation of effector-type cells in severe asthmatics. Functional studies showed that CD8+CD28- T cells had cytotoxic function.