The kinin system in exercise-induced asthma.

Seventeen asthmatic children, nine with and eight without exercise-induced asthma (EIA), and nine control non-asthmatic children were studied in an attempt to discern possible associations between the activity of the kinin system and EIA. Pulmonary function tests and clinical check-up were performed before and after 6 min of free-range running. Concomitant blood tests revealed a consistent elevation of the kallikrein levels following the exercise challenge in all experimental groups. However, only in the EIA positive group did this elevation exceed the normal laboratory range (16 +/- 7.0 mu/ml). Prekallikrein levels both before and after exercise did not exceed in any group the normal laboratory values. The findings thus suggest that provocation of EIA is associated with a certain threshold of kallikrein level below which no such symptoms are observed. EIA may be triggered only when kallikrein levels are in excess.