Serum phospholipase A2 activity in patients with aspirin-induced asthma

Abstract

Urinary excretion of leukotrienes is greater in patients with aspirin-induced asthma (AIA) than in other patients with asthma in remission, and is greater still during an aspirin-induced attack. We therefore hypothesized that increased phospholipase A2 (PLA2) activity leads to increased leukotriene synthesis when non-steroidal antiinflammatory drugs inhibit cyclooxygenase in patients with AIA, and that PLA2 activity increases further during an aspirin induced attack. To test this hypothesis, we measured the serum PLA2 activity in adult asthmatic patients, and compared the activity in those with AIA to the activity in those without AIA. The subjects were 43 patients with asthma in remission, 17 with AIA and 26 without AIA. Serum PLA2 activity was also measured before and after intravenous administration of lysine-aspirin in three patients with AIA and in one without AIA. Serum PLA2 activity was measured by radioimmunoassay. Serum PLA2 activity in patients with AIA, in those without AIA, and in healthy controls was 300.9 +/- 52.9, 294.4 +/- 65.3 and 171.7 +/- 41.8 pmol/ml/min, respectively. Serum PLA2 activity in asthmatic patients was significantly higher than in healthy controls (p < 0.01), but there was no difference between patients with and without AIA. Intravenous lysine-aspirin provoked asthmatic attacks in three patients with AIA. However, intravenous lysine-aspirin did not significantly change serum PLA2 activity in the three patients with AIA or in the patient without AIA. These results indicate that although PLA2 may be involved in the pathogenesis of bronchial asthma, it is not specific to AIA. Thus, the pathophysiology of AIA remains unclear and further investigation is needed.