Which CD8+ T-cells in asthma? Attacking or defending?

It is fairly clear that when we speak about the role of CD8+ T-cells in asthma, we have to be much more precise. Which of CD8+ T-cells described here is at fault? A combination of them? Possibly. Since respiratory viruses and allergens are common triggers in asthma, both virus-specific and antigen-specific CD8+ T-cells would be expected to contribute to the worsening and decline of lung function in asthmatic subjects [12]. However, CD8+ T-cells could also act as defending cells, thus attenuating the severity of asthma, and the mildness of the disease in the asthmatic subjects described by DEN OTTER et al. [3] would support this possibility. Whether the CD8+ T-cells play a protective or a pathogenic role is probably determined by the conditions in the local environment. For example, the presence of IL-4 produced by CD4+ T-cells is an important determinant for the shift of CD8+ T-cells to most of the different CD8+ subpopulations described. Therefore, we should not forget that the CD4+ T-cell, which is also correlated with the functional decline in the study by DEN OTTER et al. [3], remains the protagonist in orchestrating the inflammatory response in asthma. In conclusion, it would be very helpful to better understand which CD8+ cells might be playing a role in asthma before we start a campaign against this cell, always remembering that some of these CD8+ cells are effector-memory Tc-cells, keeping an eye open to possible viral infections in these very susceptible patients. Copyright ©ERS 2016.