Complement-mediated lysis of pigeon erythrocyte ghosts analysed by flow cytometry. Evidence for the involvement of a ‘threshold’ phenomenon

Publisher Website
Google Scholar
Abstract
Flow-cytometric analysis of complement-mediated lysis of antibody-coated pigeon erythrocyte ghosts containing fluorescein was carried out to determine whether lysis involved a gradual release of fluorescein or a threshold release from individual cells. Antibody-coated ghosts were comprised of 3 subpopulations identified by fluorescence and scatter (size). These were: highly fluorescent, medium scatter, medium fluorescence, high scatter and low (or zero) fluorescence, low scatter. Lysed ghosts and isolated nuclei were identified by fluorescence microscopy and scanning electron microscopy. Fluorescence distributions analyzed by flow cytometry indicated that after complement attack those ghosts remaining intact retained all their fluorescent lable. A time course of changes in ratios of the 3 subpopulations indicated that once lysis of an individual ghost was initiated, release of label was complete within 1 min; no stages of intermediary fluorescence appeared, and those ghosts remaining at the end of the experiment retained the same fluorescence intensity as control ghosts. Evidently, complement-mediated cell lysis is a threshold phenomenon, a submaximal response by a cell population representing a complete response by only some of the cells rather than a partial response by all of the cells.