Leukocyte activation in patients with venous insufficiency

Cell activation may play an important role in the production of venous insufficiency, just as leukocytes participate in the cause of venous ulcer. If activated, monocytes observed on venous endothelium can migrate into the venous wall and produce toxic metabolites and free oxygen radicals that may participate in valve destruction and venous wall weakening. At present, it remains uncertain to what degree leukocytes are actually activated in patients. This study was designed to explore the level of activation and to examine whether patient plasma contains an activator that leads to leukocyte activation of unstimulated naive leukocytes from volunteers without venous insufficiency disease.

Twenty-one patients (4 men, 17 women), who ranged in age from 34 to 69 years (mean age, 53.2 years), with chronic venous disease were compared with 16 healthy control volunteers (4 men, 12 women), who ranged in age from 18 to 65 years (mean age, 48.4 years). All the patients underwent evaluation with Doppler ultrasound scanning and were classified with the CEAP score.1 Nearly all the patients who smoked or were hypertensive were excluded. The blood types (ABO and Rh) of the controls were matched to the study group. Isolates of patient whole blood, plasma, or leukocytes were incubated with isolates of control whole blood, plasma, or leukocytes to separate actual activation from spontaneously observed activation. The granulocyte activation was measured with nitroblue tetrazolium (NBT) reduction and quantitation of granulocyte pseudopod formation. Hydrogen peroxide production in patient plasma was measured with a recently developed electrode method.

Leukocytes from healthy blood and patient plasma had significantly higher NBT-positive granulocyte counts than either patient blood, healthy blood, or patient blood incubated in healthy plasma. In a comparison of patient groups across the CEAP classes, the NBT-positive granulocyte counts were significantly greater in classes 4, 5, and 6 than in classes 2 and 3 (P <.001). Pseudopod formation was significantly greater in mixtures of granulocytes in healthy blood and patient plasma than in all other groups. There was no difference in the level of pseudopod formation in control leukocytes incubated with patient plasma in patients across the CEAP spectrum. The patient plasma produced significantly higher hydrogen peroxide values than did the controls.

These results suggest that patient plasma may contain an activating factor for granulocytes. The finding that activated neutrophils were fewer in number in patient whole blood than in healthy blood incubated in patient plasma could suggest that activated neutrophils in patients with chronic venous insufficiency might be trapped in the peripheral circulation. It is unknown what factors in the plasma might induce activation of naive neutrophils, but such activators could possibly be important in the pathogenesis of primary venous dysfunction and the development of chronic venous insufficiency.