Temporal dynamics of peripheral neutrophil and lymphocytes following acute ischemic stroke

Abstract

Background: The immune response to acute ischemic stroke (AIS) is implicated in diagnosis, prognosis, and intervention; however, the temporal dynamics of leukocytes following AIS are poorly understood. The purpose of this study was to characterize peripheral leukocyte dynamics following AIS among individuals with poor and favorable outcomes.

Methods: A retrospective chart review was conducted among patients with a diagnosis of AIS who were treated at a comprehensive stroke center across a 3-year timeframe. Groups were defined according to stroke outcomes. Patients with poor outcomes were distinguished from those with favorable outcomes by discharge National Institute of Health Stroke Score, infarct size, and Modified Rankin Scale. Leukocyte counts were compared among controls and AIS outcome groups.

Results: The neutrophil-lymphocyte ratio (NLR) calculated at 48-72 h post-AIS was identified as the strongest predictor of outcome. NLR was significantly higher in the poor outcome group (8.68 ± 0.93) compared with both the favorable outcome (4.5 ± 0.51, p = 0.009) and control group (4.33 ± 0.66, p < 0.001). Patients with a 48-72 h NLR ≥ 4.58 were 5.58 times more likely to have a poor outcome than AIS patients with an NLR < 4.58.

Conclusions: The results of this study improve the understanding of the immune response in AIS. Low neutrophil count relative to high lymphocyte count at 48-72 h post-AIS should be considered a predictor of a favorable stroke outcome. Conversely, high neutrophil count relative to low lymphocyte count at 48-72 h post-AIS should be considered a predictor of a poor stroke outcome.

Keywords: Immune; Leukocyte; Neutrophil; Neutrophil-lymphocyte ratio; Stroke.

Fig. 1

Temporal neutrophil dynamics post-AIS by outcome group. Neutrophil count (mean ± SEM) is plotted over time at three intervals. Control is displayed in black, favorable outcome acute ischemic stroke (AIS) in green, and poor outcome AIS in red. The gray dashed line represents the upper limit of normal neutrophil count in a healthy individual. Statistical significance is set at p < 0.05, and *represents a significant different between control and favorable outcome AIS, #represents a significant different between control and poor outcome AIS, and ‡represents a significant different between poor and favorable outcome AIS groups

Fig. 2

Temporal lymphocyte dynamics post-AIS by outcome group. Lymphocyte count (mean ± SEM) is plotted over time at three intervals. Control is displayed in black, favorable outcome acute ischemic stroke (AIS) in green, and poor outcome AIS in red. Statistical significance is set at p < 0.05, and ‡represents a significant different between poor and favorable outcome AIS groups

Fig. 3

Change in neutrophil-lymphocyte ratio post-AIS by outcome group. Neutrophil-lymphocyte ratio (NLR) is plotted over time at three intervals. Control is displayed in black, favorable outcome acute ischemic stroke (AIS) in green, and poor outcome AIS in red. The dashed line represents the upper limit of normal neutrophil count in a healthy individual. Statistical significance is set at p < 0.05, and #represents a significant different between control and poor outcome AIS, and ‡represents a significant different between poor and favorable outcome AIS groups

Fig. 4

Neutrophil dynamics by outcome group and infarct volume. Neutrophil count (mean ± SEM) is plotted at three intervals. Favorable outcome acute ischemic stroke (AIS) with small infarct is represented as an open circle, favorable outcome acute AIS with large infarct as a filled circle, poor outcome acute AIS with small infarct as an open triangle, and poor outcome acute AIS with large infarct as a filled triangle