White Blood Cell Behavior in the Cerebral Microcirculation

Abstract

The role of white blood cells in acute cerebral disorders such as ischemia, stroke, or inflammation is not understood. Activated neutrophils might be involved, for example, in damage to the cerebrovascular endothelium and opening of the blood-brain barrier (Unterberg et al. 1987). Leukocytes are known to obstruct capillaries in heart muscle after reversible ischemia (Engler et al. 1983) and, thus, could be responsible for the no-reflow phenomenon, which inhibits nutritive flow and oxygen delivery. These observations are compatible with the investigations of Ernst et al. (1987), who found a reduced fluidity of white blood cells in vitro from stroke patients, which might be attributable to an increased adhesiveness and/or a decreased deformability of leukocytes in the cerebral microcirculation. White blood cell adherence to the endothelial surface, however, is not only seen in ischemia (Hallenbeck et al. 1986), but also in other disorders of the brain. In subarachnoid hemorrhage, adhering leukocytes are assumed to cause inflammation of the vascular wall and thus to be involved in the pathogenesis of cerebral vasospasm (Nazar et al. 1988).