Alteration of Human Leukocyte Chernotaxis, Chemiluminescence, and HMP Shunt Activity Caused By Mechanical Trauma

The effect of graded shear stress exposure (0 to 800 dynes/cm² at 35°C) on human leukocyte function was examined in vitro, using a concentric cylinder viscometer. Boyden Chamber chemotaxis was significantly reduced at stress levels above 150 dynes/cm², and was over a factor of three lower after exposure to trauma levels of 450 dynes/cm² Hexose monophosphate (HMP) shunt activity following particle ingestion was also significantly lower after exposure to shear stresses of 150 dynes/cm² or more for ten minutes. PMN chemiluminescence was reduced following stress trauma of 450 dynes/cm² using whole blood, and after 150 dynes/cm² using leukocyte suspensions. All the functional alterations reported appear to be bulk shear stress effects and not due to surface interaction, as changing the surface-to-volume ratio in the viscometer by over a factor of three did not change the damage caused at a given stress level. These functional alterations caused by mechanical trauma may be important in hemodialysis, cardiopulmonary bypass, venovenous perfu-sion, and in any blood-contacting artificial organ. The stress levels required for damage are of the same order as those required for platelet functional alteration, and much lower than those required for erythrocyte hemolysis for the same exposure times.