title: Effects of in vivo ultrasound hyperthermia on natural killer cell cytotoxicity in the hamster.
abstract: The effects of in vivo ultrasound irradiation of the spleen on immunological functions were assessed with an in vitro natural killer (NK) cell cytotoxic assay. Anesthetized hamsters were exposed to 1 MHz ultrasound at intensity levels currently being used clinically for therapeutic diathermy and hyperthermia (1-5 W/cm2, for 500 sec with constant beam scanning). Hyperthermic levels in the spleen ranged from 38-43 degrees C. Significant depression of natural killer (NK) cell activity was seen 4 h after spleen irradiation as compared to sham irradiated and normal animals. A return towards normal levels was observed in experimental groups at 24 h after exposure. Sham and normal animals were not significantly different in NK activity, indicating no significant stress-related immunosuppressive effects due to handling. Differential leukocyte counts taken for each exposure condition showed significant lymphopenia at 4, 8, and 16 h after exposure, near normal levels at 24 h, and complete recovery by 48 h. The number of circulating mononuclear cells at 4 h showed a dose-related suppression as the exposure intensities were increased.
mesh_terms: D000818:Animals; D001831:Body Temperature; D006224:Cricetinae; D003602:Cytotoxicity, Immunologic; D006979:Hyperthermia, Induced; D007165:Immunosuppression Therapy / Q000379:methods; D007694:Killer Cells, Natural / Q000276:immunology*; D007958:Leukocyte Count; D008647:Mesocricetus; D013154:Spleen / Q000502:physiology; D013997:Time Factors; D014465:Ultrasonics