Plasma levels of leukotriene B4 in asthmatic patients.

We measured changes in plasma levels of leukotriene B4 (LTB4) during the clinical course of bronchial asthma. Samples of 2 ml of blood were drawn from the femoral artery of 5 patients on two occasions: a) during remission and b) during an attack. LTB4 levels were determined by a combination of high-performance chromatography with radioimmunoassay. In the 5 asthmatic patients, the LTB4 levels (mean +/- S.D.) on the two occasions were respectively 34.2 +/- 8.6 and 118.0 +/- 49.5 pg/ml. In contrast, the mean LTB4 level of 5 control subjects was 23.5 +/- 3.77 pg/ml. LTB4 levels differed significantly between remission and an attack. The corresponding mean PaCO2 values on the two occasions were respectively 37.7 +/- 1.8 and 47.3 +/- 2.2 mmHg. LTB4 showed good correlation with PaCO2. We therefore suggest that leukotriene B4 levels in arterial blood are associated with the severity of asthmatic attacks.