Effects of antineutrophil serum (ANS) on posttraumatic brain oedema in rats

The role of white blood cells in acute central nervous system disorders, such as stroke or traumatic injury is poorly understood. In this experimental study the effect of neutropenia on posttraumatic brain oedema was investigated. Polyclonal antiserum against polymorphonuclear leukocytes was used to induce neutropenia. Control animals received normal serum or no treatment at all. Hemispheric swelling and brain water content after cryo-injury to the exposed left cerebral hemisphere was gravimetrically assessed, and by the wet weight-dry weight method. Administration of anti-neutrophil serum led to a significant reduction of circulating neutrophils. In untreated animals or in rats receiving normal serum, hemispheric swelling of the brain was 7.26 +/- 0.35% or 8.52 +/- 0.26%, respectively. Neutropenia induced by anti-neutrophil serum resulted in a significant increase in hemispheric swelling to 11.44 +/- 0.84% (p less than 0.001). It may be noted, however, that the enhancement of brain swelling by neutropenia was not obvious when comparing the water contents of the affected hemispheres of animals subjected to cold injury with and without anti-neutrophil serum. The enhancement of brain oedema by neutropenia suggests a protective function of neutrophils against extravasation in the presence of a broken blood-brain barrier.