NEUTROPHIL ACTIVATION IN EXPERIMENTAL VENOUS HYPERTENSION

Objective: To investigate the white cell trapping hypothesis of venous ulceration by measuring plasma lactoferrin as a marker of neutrophil degranulation in normal volunteers in two experimental models of venou s hypertension. Design: A prospective study of volunteers with no hist ory or clinical evidence of venous disease. Setting: The Middlesex Hos pital Vascular Laboratory, Mortimer Street, London W1N 8AA, UK. Patien ts: Volunteers within the Middlesex Hospital Vascular Laboratory with no history or clinical findings of venous or arterial disease, no othe r systemic disease, on no medication known to alter white cell activit y, and with no recent infection. Intervention: Venous blood was taken from cannulae in both feet and the right arm for a neutrophil count an d plasma lactoferrin, measured using an ELISA, during application of a tourniquet to 80 mmHG for 30 min to the right leg while supine, 5 min after release of tourniquet, and then during a 30 min period of stand ing. Results: During application of a tourniquet to the right leg ther e was a significant rise in plasma lactoferrin and in lactoferrin corr ected for the neutrophil count (p <0.05, Wilcoxon). In the unoccluded leg, although plasma lactoferrin rose, this was not significant when c orrected for the rise in neutrophil count. After standing for 30 min, the lactoferrin and neutrophil count increased in all three limbs; cor rected lactoferrin showed a significant increase in the legs (p <0.02) , though not in the arm. Conclusion: Increased neutrolphil degranulati on occurs during periods of short-term venous hypertension in normal v olunteers, in keeping with the white cell trapping hypothesis.