NEUTROPHILS ARE THE INITIAL CELL-TYPE IDENTIFIED IN DEEP VENOUS THROMBOSIS INDUCED VEIN WALL INFLAMMATION

Venous thrombosis and inflammation are interrelated. The authors hypot hesized that inferior vena cava thrombosis results in a predictable ve in wall inflammatory response, characterized by early neutrophil infil tration. Thrombosis was induced in rats by placement of an inferior ve na cave ligature with branch ligation. Animals were killed at baseline , 6 hrs, day 2, and day 6. Analysis included vein wall morphometrics, myeloperoxidase activity, and fluorescence activated cell sorting. At 6 hrs, there was an increase in neutrophils and lymphocytes as compare d to sham animals (p < 0.0001 for neutrophils, p < 0.05 for lymphocyte s). By day 2, only neutrophils were elevated in the experimental group s (experimental = 75.5 cells/5 high power fields vs. 9.6 cells/5 high power fields in shams, p < 0.0001). Myeloperoxidase activity in the ex perimental group was greater than shams on day 2 (34.7 Delta optical d ensity/min vs. 5.9 Delta optical density/min, p < 0.0001). Fluorescenc e activated cell sorting of the neutrophil marker at 6 hrs confirmed t he increase in neutrophils (experimental = 63.1%, shams = 39.1%, p < 0 .0001), and peaked on day 2 (71.9%). This study suggests that 1) neutr ophils are elevated early during the inflammatory response due to thro mbus initiation, and 2) neutrophils, because of their early predominan ce, likely contributed to vein wall injury during venous thrombosis.