Leukocytes and Stroke

One of the earliest inflammatory responses to stroke identified in patients is an increase in peripheral leukocyte counts. Leukocyte increases have been observed within 24h of an ischaemic event and some studies report a sustained elevation, versus controls, for at least one week. It appears that neutrophils are the earliest leukocytes to respond, and their levels correlate with infarct volume. Selective labelling of neutrophils indicates that they are recruited to the brain within 24h of symptom onset. Increases in the levels of circulating monocytes are also observed, but this tends to be delayed compared to the neutrophil response, typically being seen more than three days post-stroke. Dendritic cells, which are key antigen presenting cells and immunregulators in the body, have also been shown to infiltrate into the brains of patients after cerebral ischemia, whilst circulating levels decrease.

Reference: Inflammation and brain injury: Acute cerebral ischaemia, peripheral and central inflammation 10.1016/j.bbi.2009.09.010