The effect of exercise on basophil histamine release in patients with bronchial asthma

There is increasing evidence for the role of basophils in allergic bronchial asthma. We studied the potential role of basophils in the pathogenesis of post-exercise-induced bronchoconstriction by measuring the histamine release from basophils both spontaneously and following ConA, FMLP, anti-IgE and TPA treatment. Two groups of patients with allergic asthma were studied: group I consisted of 8 patients with an exercise-induced fall in FEV1 of 20% or more, and group II had 7 patients with bronchial asthma who had less than a 5% fall in FEV1 following exercise. The mean spontaneous histamine release (SHR%) from basophils for group I was significantly larger than that of group II both before as well as at 5-10 and 60 min following exercise. The SHR% at baseline was 25 +/- 10 in group I (mean +/- SD) and 15 +/- 5 in group II (mean +/- SD). At 5-10 min following exercise it was 24 +/- 6 in group I and 11 +/- 2 in group II, while at 60 min following exercise it was 24 +/- 6 in group I and 17 +/- 2 in group II. There was no significant difference between the two groups in the effect of ConA, FMLP, anti-IgE or TPA treatment on basophil histamine release. The enhanced bronchoconstriction by exercise did not affect histamine release either spontaneously or following those 4 stimuli. It was concluded that, although patients with exercise-induced asthma have a greater degree of spontaneous histamine release, this is not affected by induced bronchoconstriction, a finding which does not support a role for basophils in exercise-induced asthma.