Depression of phagocytosis by ultrasound

Abstract Swiss mice insonated with a 2 megaHertz (MHz) wave at an energy level of 8.9-milliwatts/square centimeter (mW/cm 2 ) applied over the liver had an impaired ability to clear injected colloidal carbon from their blood compared to untreated mice. Mice evaluated immediately after treatment had a depressed phagocytic index (K) and clearance half-time ( T 1 2 ) but their phagocytic index corrected for liver and spleen weight (α) was normal. All three parameters deviated from normal if the clearance assay was conducted 48 or 72 hr after insonation, indicating a latency of the effect of ultrasound on the phagocytic system. The demonstration that peritoneal macrophages exposed in vivo to ultrasound also had depressed phagocytic abilities indicated that the reduced clearance of carbon from the blood of mice was not entirely due to damage to the liver.