Distribution and cytokine production of CD4 and CD8 T-lymphocyte subsets in patients with acute asthma attacks.

Background: The activation of T cells and the elevation of Th2-type cytokines have been observed in asthmatic patients, but the relative role of CD4 and CD8 T cell is still unclear.
Objective: To investigate the role of T cell subset in patients with acute asthma attacks, we analyzed the distribution, activation status, and cytokine production of CD4 and CD8 cells.
Methods: The percentages of the CD4 and CD8 cell in peripheral blood (PB) and bronchoalveolar lavage (BAL) fluid were analyzed by flow cytometry. The cytokines (IL-4, IL-5, and IFN-gamma) and soluble IL-2 receptor (sIL-2R) were measured by ELISA in culture supernatants of CD4 and CD8 cells purified from PB.
Results: The CD4/CD8 ratio in PB of asthmatic patients was significantly higher than that of controls, which was significantly reduced after treatment. In contrast, there was a tendency to high percentage of CD8 cells in asthmatic patients as compared with controls in BAL, which resulted in a decreased CD4/CD8 ratio. Comparing the T cell subsets in BAL with paired PB in asthma, the CD4 cells were higher in PB, but CD8 cells were higher in BAL. The IL-4, IL-5, and sIL-2R produced by CD4 cells were significantly higher than those produced by CD8 cells in asthmatic patients.
Conclusions: Our results provide evidence that activated CD4 T cells increase and produce type 2 cytokines in PB, but CD8 T cell are more sequestrated than CD4 T cells in the airway during an acute asthma attack.