Introduction: Rapidly sorting patients with large vessel occlusion (LVO) ischemic stroke is crucial to ensure efficient transfers to stroke units. Peripheral monocyte subsets (classical-Mon1, intermediate-Mon2, non-classical-Mon3) could be interesting candidate biomarkers in this setting: their profiles in the first hours after stroke symptom onset are unknown. Aim: To characterize monocyte subsets in patients admitted to emergency units for acute stroke suspicion Methods: BOOST (“Biomarkers-algOrithm-for-strOke-diagnoSis-and-Treatment-resistance-prediction”, NCT04726839) is a prospective multicenter cohort. Adult patients with symptoms suggesting acute stroke within the last 24 hours were included. Blood was collected upon admission before brain imaging. Flow-cytometry (FCM) was performed on fresh blood with gating based on CD45/CD14/CD16/CD91 as well as on activation markers (CD62L/CD11b/CD86/HLA-DR/CCR2/ICAM-1/CX3CR1/TF). Results: Of the 298 consecutive patients tested, mean age 64.0±18.6 years, 64 (21.5%) had LVO stroke vs 234 (78.5%) other diagnosis (non-LVO ischemic stroke, cerebral venous thrombosis, intracranial hemorrhage, transient ischemic attack and stroke mimics). The median time from symptom onset to sampling was 2.3 hours. We found a significantly lower proportion of Mon3 (geometric mean) (−47%, p=0.0093) and a higher proportion of Mon1 (+1.6%, p=0.0296), suggesting earlier Mon1 mobilization and patrolling Mon3 consumption in LVO-patients versus those without. Using linear-mixed-effect model, significant differences in ICAM-1 and HLA-DR expression on monocyte subsets were evidenced between LVO and other patients. Conclusions: This is the first study to evidence monocyte subset differences in LVO vs non-LVO patients at the time of admission, indicating an acute systemic response in LVO. Whether Mon assessment would add value for LVO-diagnosis remains to be determined.
Heng et al. (Mon,) studied this question.