Role of leukocyte adhesion in clinical stroke.

Activated neutrophils appear to be directly involved in potentiating central nervous system ischemic injury. After initial endothelial adherence, neutrophils can produce capillary plugging with subsequent parenchymal infiltration and resulting cytotoxic neuronal injury. We used an in vitro leukocyte adherence assay to determine if adhesion is increased in acute stroke (within 72 h) or in patients at high risk for stroke (two or more risk factors) compared to matched controls. Neutrophils were isolated using density gradient centrifugation, and adherence to laminin or fibronectin was determined using a myeloperoxidase assay. The adhesion to laminin was significantly higher (p < 0.05) in the stroke group (23.6 ± 4.3; n = 14) compared to controls (9.7 ± 2.3; n = 12), with the risk group being intermediate (16.3 ± 4.3; n = 14). Total WBC counts were significantly higher in the stroke 8.0 ± 0.72 and risk 7.8 ± 0.41 groups (p < 0.05), compared to controls 5.3 ± 0.27. These data indicate that neutrophil adherence is increased in acute stroke and suggests that the total number of potentially adherent cells (total neutrophils times percent adherent cells) is greatly increased.