LEUKOTRIENE B-4 LEVELS IN THE ARTERIAL BLOOD OF ASTHMATIC-PATIENTS AND THE EFFECTS OF PREDNISOLONE

Prednisolone is very effective in controlling wheezing attacks of bron chial asthma, but its mechanism and the pathogenic role of leukotriene B-4 remain unclear. We measured changes in plasma levels of leukotrie ne B-4 in an open study during the clinical course of bronchial asthma , with or without water-soluble prednisolone treatment. Two millilitre s of blood was drawn from the radial artery of patients on three occas ions: 1) during remission; 2) on admission to hospital with an asthma attack; and 3) 2 days after admission and treatment with intravenous p rednisolone (1,000 mg-day(-1)). Leukotriene B-4 was detected by chroma tographic fractionation and radioimmunoassay. In 11 asthmatic patients , leukotriene B-4 levels on the three occasions were 26.8 (10.7), 106. 0 (39.9) and 51.6 (20.2) pg ml(-1) (mean (SD)), respectively, In contr ast, the mean leukotriene B-4 level of 10 normal controls was 35.9 (10 .5) pg ml(-1). Leukotriene B-4 levels differed significantly between r emission and attack treated without prednisolone, and between attacks treated with and without prednisolone. Mean arterial carbon dioxide (P aCO2) values were 4.8 (0.4) kPa (36.0 (3.0) mmHg), 6.1 (0.4) kPa (45.6 (2.9) mmHg), and 5.5 (0.3) kPa (41.6 (2.0) mmHg), respectively. There were significant differences between these mean PaCO2 values. The mea n leukotriene B-4 levels on the three occasions were correlated with t he mean PaCO2 values. Thus, leukotriene B-4 levels in arterial blood r eflect the severity of asthmatic attacks and may be affected by intrav enous prednisolone.