Increase in killer-specific secretory protein of 37 kDa in bronchoalveolar lavage fluid of allergen-challenged patients with atopic asthma

Summary Background Atopic asthma is linked to a T-helper type 2 dominated pathogenesis, but there is increasing evidence of Th1/Tc1-mediated processes in the aetiopathology of asthma. Killer-specific secretory protein of 37 kDa (Ksp37) is expressed in cytotoxic lymphocytes, selectively in the effector subsets of CD8+- and CD4+ T lymphocytes and in CD16+/CD56dim natural killer cells and γ/δ T cells. This effector cell-specific expression of Ksp37 and its coexpression with perforin suggest that Ksp37 might be involved in processes mediated by cytotoxic cells. Objective We hypothesize that Ksp37 could indicate the involvement of cytotoxic lymphocytes in the pathogenesis of atopic asthma, and investigated Ksp37 concentration in bronchoalveolar lavage fluid (BALF) collected 10 min, 18, 42 or 162 h after segmental allergen provocation and in serum of patients with atopic asthma (n=25). Methods Ksp37 concentrations in BALF and serum were detected by ELISA. Flow cytometric analysis was used to assess numbers and cell subsets in BALF. Results Ksp37 increased significantly in BALF 10 min, 18 and 42 h, but not 162 h after allergen challenge compared with saline-challenged controls, while Ksp37 serum levels did not change significantly at all time-points. In addition, the increase in Ksp37 concentrations in BALF correlated with the corresponding numbers of lymphocytes. Conclusions We conclude that Ksp37 level increased in BALF 10 min, 18 and 42 h after allergen challenge but not in peripheral blood. Our findings suggest that segmental allergen challenge in asthma is associated with an increase in Ksp37 concentrations in BALF and an influx of potentially cytotoxic T lymphocytes into the lungs.