Temporal Trends in the Levels of Peripherally Circulating Leukocyte Subtypes in the Hours after Ischemic Stroke

Background: Leukocyte-mediated neuroinflammation may affect outcomes after ischemic stroke. Aims: To explore temporal changes in levels of peripherally circulating leukocyte subtypes in the early hours after ischemic stroke in humans. Methods: Retrospective analysis of a single-center database of consecutive thrombolysis cases for acute ischemic stroke (AIS). Multivariable regression analysis was used to explore temporal changes in the levels of peripherally circulating leukocyte subtypes in the hours immediately after ischemic stroke. A natural logarithm transformation was used to achieve normally distributed residuals, and adjustment was made for the severity of stroke, blood glucose concentration, sex, and age. Results: Blood samples were taken a median time of approximately 2 hours after stroke symptom onset. Median peripheral neutrophil and lymphocyte counts on admission were 4.8 x 10(9) cells per liter (interquartile range [IQR], 3.6-7.2 x 10(9) cells per liter) and 1.9 x 10(9) cells per liter (IQR, 1.3-2.6 x 10(9) cells per liter), respectively. Multivariable regression analysis revealed that after adjustment there was a linear increase in the natural logarithm of the peripheral neutrophil count (P < .01), with a linear decrease in the natural logarithm of the peripheral lymphocyte count (P < .01) in the hours immediately after stroke onset. No significant temporal associations were found between the levels of the other peripherally circulating leukocyte subtypes. Conclusions: Immediately after ischemic stroke, there is an exponential increase in the neutrophil count and an exponential decrease in the lymphocyte count.