Platelet kinetics in asthmatic patients with and without aspirin intolerance

A reduced platelet survival time has been described in asthmatic patients. There is also good evidence that platelets are involved in aspirin induced asthma. Since aspirin intolerant patients usually suffer from an active disease and often require anti-inflammatory treatment, it has been suggested that platelet survival time may be shorter in aspirin intolerant asthmatic subjects than in aspirin tolerant subjects. The objective of this study was to investigate this hypothesis.

Thirteen asthmatic subjects (six aspirin tolerant and seven aspirin intolerant) in a stable clinical condition and ten healthy subjects were studied. Platelet kinetics and survival time were measured with indium-111 labelled autologous platelets.

Mean (SD) platelet sequestration ratios in the spleen and liver were lower in asthmatic (2.3 (0.9) and 0.6 (0.2) respectively) than in healthy subjects (3.2 (0.7) and 1.1 (0.4) respectively). However, mean (SD) platelet survival time in asthmatic subjects (8 (2.7) days) did not differ from that in healthy subjects (7.6 (1.1) days). No differences were observed in platelet kinetics between aspirin tolerant and aspirin intolerant patients.

These results suggest the existence of an active non-splenic pool of platelets in patients with asthma. However, they failed to show platelet kinetic differences among asthmatic subjects with and without aspirin intolerance and do not support previous studies suggesting an altered platelet survival in stable asthma.