Elevation of soluble intercellular adhesion molecule-1 levels in symptomatic and asymptomatic carotid atherosclerosis

OBJECTIVE: Recent data suggest that the increased expression of intercellul ar adhesion molecule-1 (ICAM-1) in atherosclerotic plaque taken from the ca rotid bifurcation correlates with the development of neurological symptoms. As a result, the authors sought to compare the serum levels of soluble for ms of ICAM-1 (sICAM-1) in patients who were asymptomatic with those who wer e symptomatic for carotid artery stenosis as well as in patients who were m atched in terms of sex, age, and risk factors who did not have carotid arte ry disease. METHODS: Using enzyme-linked immunosorbent assay, serum sICAM-1 levels were prospectively determined in 54 patients scheduled to undergo carotid endar terectomy for either symptomatic or asymptomatic high-grade stenosis (great er than or equal to 60%) and in 5 additional patient controls. Data are exp ressed as mean +/- standard error of the mean, with significance defined as P < 0.05 using the Mann-Whitney two-tailed test for two-column comparison or analysis of variance and Fisher protected least significant difference t est. RESULTS: Using a univariate model, serum sICAM-1 levels were significantly elevated in patients with carotid artery stenosis as compared with control patients without stenosis (347 <plus/minus> 15 ng/ml versus 216 +/- 8.2 ng/ ml) (P < 0.01). When the asymptomatic and symptomatic patients with carotid artery stenosis were considered separately, these levels were still elevat ed relative to those of control patients (asymptomatic [312 <plus/minus> 18 ng/ml] and symptomatic [376 +/- 22 ng/ml] patients; P = 0.06 for asymptoma tic versus control patients, P < 0.01 for symptomatic versus control patien ts). Symptomatic patients also had significantly elevated sICAM-1 levels as compared with asymptomatic patients (P < 0.05). Despite the fact that fema le patients demonstrated higher ICAM-1 levels than male patients (P < 0.05) , sex, age, and risk factors such as the presence of hypercholesterolemia, diabetes, hypertension, or a history of smoking did not confound these find ings. CONCLUSION: Levels of sICAM-1 are higher in patients with carotid stenosis than in control patients. Symptomatic patients demonstrate significantly el evated levels as compared with asymptomatic patients. These data support th e contention that ICAM-1 is a reliable marker of carotid disease progressio n and suggest that serum levels may be useful in following certain asymptom atic patients.