CIRCULATING INTRACELLULAR ADHESION MOLECULE-1 CONCENTRATIONS FOLLOWING BRONCHIAL PROVOCATION IN ATOPIC ASTHMA

A house dust bronchial provocation test (BPT) was used to investigate the effect of allergen-induced airway inflammation and airway hyperres ponsiveness (AHR) on the level of circulating intracellular adhesion m olecule-1 (c-ICAM-1). The concentration of c-ICAM-1 was measured by th e sandwich ELISA while the level of eosinophil cationic protein (ECP) in the sputum was determined by RTA. The parameter used for quantifica tion of AHR was the minimum dose of methacholine (Mch) required to pro duce a fall in respiratory resistance and was expressed as log D-min. Fourteen subjects with mild atopic asthma participated in this study. Ten patients (dual asthmatic response group; DAR group) developed a la te asthmatic response (LAR) following an immediate asthmatic response (IAR). Four subjects (IAR alone group) exhibited only IAR following BP T. In both groups, the mean baseline concentration of c-ICAM-1 did not change 6 h after BPT (from 195.3+/-20.3 to 220.9+/-27.6 and from 215. 5+/-23.5 to 231.3+/-30.5 ng/ml, respectively). However, BPT produced a significant increase in the mean concentration of c-ICAM-1 24 h later in the DAR group (257.3+/-41.14 ng/ml, p < 0.05), but not in the IAR alone group (225.5+/-18.1 ng/ml). BPT also increased ECP levels in the sputum from a baseline value 24 h after BPT in the DBR group (from 30 .2+/-10.1 to 68.8+/-19.8 ng/ml; p<0.05), but not in the IAR alone grou p (from 28.1+/-8.3 to 43.3+/-23.7 ng/ml). There was a significant (p<0 .05) correlation between c-ICAM-1-concentrations and sputum ECP levels 24 h after BPT in each group. Furthermore an inverse and significant (p<0.05) correlation was found between c-ICAM-1 concentrations and per cent changes in log D-min 24 h after BPT in each group. Our results su ggest that increased concentrations of c-ICAM-1 after BPT may reflect the upregulated expression of airway ICAM-1 during allergen-induced ai rway inflammation. We propose that c-ICAM-1 is a useful marker for all ergic inflammation, particularly that of eosinophilic infiltration int o the airway, an essential feature of asthma.