Transient poration and cell surface receptor removal from human lymphocytes in vitro by 1 MHZ ultrasound

The study objective was to gain insight into ultrasound-induced, sub-lytic cell surface modifications. Two primary hypotheses were tested by how cytom etric methods; viz,, sonication will: 1, remove all or part of a specific c ell surface marker in lymphocytes surviving insonation, and 2, induce trans ient pores in the cell membranes of some surviving cells. RPMI 1788 human l ymphocytes were exposed in vitro to 1-MHz, continuous-wave ultrasound (simi lar to 8 W/cm(2) I-SP) for 30 s, which lysed similar to 50% of the cells, I nsonation: 1, altered cell morphology, increasing the population of cells o f reduced size but high structure (designated as population R2), many of wh ich were nonviable, and diminishing the population of cells of large size a nd high structure (designated as population R1), most of which were viable, 2, diminished the fluorescence signal from the pan B lymphocyte marker CD1 9 in populations R1 and R2 to equivalent extents, and 3, increased by simil ar to 7-fold the number of transiently permeabilized cells in R1, as eviden ced by simultaneous uptake of propidium iodide and fluorescein diacetate, T he results indicate that ultrasound-induced CD19 removal from R1 cells can occur without accompanying gross membrane loss. The cell morphology/mortali ty shifts indicate that the ultrasound-induced morphological change is asso ciated with lethal membrane poration, suggesting that the diminished CD19 f luorescence signal from insonated R2 cells arises partly by simultaneous lo ss of membrane fragments, CD19 and cytoplasm. (C) 1999 World Federation for Ultrasound in Medicine & Biology.