Lack of effect of pulsed ultrasound on ABO antigens of human erythrocytes in vitro.

The efficacy of pulsed ultrasound in removing ABO blood group antigens from human erythrocytes was investigated in vitro. Cell suspensions were exposed to 5.25 MHz focused ultrasound with 1.23 microseconds pulses, at 0, 20, and 37 degrees C using spatial peak, pulse average intensities of 11, 126, and 1000 W/cm2 and pulse spacings of 10, 100, and 1000 microseconds. A second experiment involved application of 7.5 MHz pulses of 0.77 microseconds duration and 8 W/cm2 SPPA intensity which were spaced 1.25 ms apart. Exposed cells were tested for agglutination by antibody to determine changes in antigen expression. In addition, supernates from exposed cells were tested for the presence of soluble antigen. A sensitive capillary tube agglutination technique was developed for these experiments. No detectable antigen removal occurred as a result of any of the pulsed ultrasound exposures as compared to sham exposures. A positive control, which employed antigenic material prepared from cells disrupted by ultrasonic cavitation, indicated that the assay could detect the soluble antigen equivalent of about one cell in 10,000.