Successful thrombolytic therapy is associated with increased granulocyte CD15 expression and reduced stroke‐induced immunosuppression

OBJECTIVES: Stroke‐induced immunosuppression (SIIS) increases the risk of poststroke infections. We aimed to determine whether failed versus successful thrombolytic therapy (TT) resulted in SIIS‐associated changes in peripheral granulocyte markers at 1 week following the insult. METHODS: We collected peripheral blood samples from 19 patients with acute ischemic stroke undergoing TT within 6 h after the onset of their first symptoms and 7 days after the insult. Age‐matched controls were sampled on one occasion. We compared the expression of CD15 and CD64 on monocytes, granulocytes, and lymphocytes using flow cytometry. RESULTS: The proportion of granulocytes and CD15+ granulocytes was comparable between controls and stroke patients at both time points. While the proportion of CD15bright granulocytes was also comparable, the mean fluorescence intensity (MFI) of CD15 on this subset was reduced in stroke patients by day 7 but was overall higher at both time points compared to controls. The MFI of CD15 on granulocytes was lower in stroke patients with failed TT than in those with successful TT 1 week after the insult. CONCLUSIONS: Our current results indicate that TT may not only acutely reduce the systemic inflammatory response following stroke but may also play a role in reversing SIIS at a later stage following the insult, as reflected by the higher expression of the CD15 marker on granulocytes following successful TT.